SH(1)                                                       SH(1)

     NAME
          ksh - Korn shell, the not standard command programming
          language

     SYNOPSIS
          ksh [ -acefhikmnorstuvx ] [ -o option ] ...  [ arg  ... ]

     DESCRIPTION
          Ksh is a command programming language that executes commands
          read from a terminal or a file.  Rsh is a restricted version
          of the standard command interpreter sh; it is used to set up
          login names and execution environments whose capabilities
          are more controlled than those of the standard shell.  See
          Invocation below for the meaning of arguments to the shell.

        Definitions.
          A metacharacter is one of the following characters:

               ;   &   (   )   |   <   >   new-line   space   tab

          A blank is a tab or a space.  An identifier is a sequence of
          letters, digits, or underscores starting with a letter or
          underscore.  Identifiers are used as names for aliases,
          functions, and named parameters. A word is a sequence of
          characters separated by one or more non-quoted
          metacharacters.

        Commands.
          A simple-command is a sequence of blank separated words
          which may be preceded by a parameter assignment list.  (See
          Environment below).  The first word specifies the name of
          the command to be executed.  Except as specified below, the
          remaining words are passed as arguments to the invoked com-
          mand.  The command name is passed as argument 0 (see
          exec(2)). The value of a simple-command is its exit status
          if it terminates normally, or (octal) 200+status if it ter-
          minates abnormally (see signal(2) for a list of status val-
          ues).

          A pipeline is a sequence of one or more commands separated
          by |.  The standard output of each command but the last is
          connected by a pipe(2) to the standard input of the next
          command.  Each command is run as a separate process; the
          shell waits for the last command to terminate.  The exit
          status of a pipeline is the exit status of the last command.

          A list is a sequence of one or more pipelines separated by
          ;, &, &&, or ||, and optionally terminated by ;, &, or |&.
          Of these five symbols, ;, &, and |& have equal precedence,
          which is lower than that of && and ||.  The symbols && and

     SH(1)                                                       SH(1)

          || also have equal precedence.  A semicolon (;) causes
          sequential execution of the preceding pipeline; an ampersand
          (&) causes asynchronous execution of the preceding pipeline
          (i.e., the shell does not wait for that pipeline to finish).
          The symbol |& causes asynchronous execution of the preceding
          command or pipeline with a two-way pipe established to the
          parent shell.  The standard input and output of the spawned
          command can be written to and read from by the parent Shell
          using the -p option of the special commands read and print
          described later.  Only one such command can be active at any
          given time.  The symbol && (||) causes the list following it
          to be executed only if the preceding pipeline returns a zero
          (non-zero) value.  An arbitrary number of new-lines may
          appear in a list, instead of semicolons, to delimit com-
          mands.

          A command is either a simple-command or one of the follow-
          ing.  Unless otherwise stated, the value returned by a com-
          mand is that of the last simple-command executed in the com-
          mand.

          for identifier [ in word ... ] do list done
               Each time a for command is executed, identifier is set
               to the next word taken from the in word list.  If in
               word ...  is omitted, then the for command executes the
               do list once for each positional parameter that is set
               (see Parameter Substitution below).  Execution ends
               when there are no more words in the list.

          select identifier [ in word ... ] do list done
               A select command prints on standard error (file
               descriptor 2), the set of words, each preceded by a
               number.  If in word ...  is omitted, then the posi-
               tional parameters are used instead (see Parameter
               Substitution below).  The PS3 prompt is printed and a
               line is read from the standard input.  If this line
               consists of the number of one of the listed words, then
               the value of the parameter identifier is set to the
               word corresponding to this number.  If this line is
               empty the selection list is printed again.  Otherwise
               the value of the parameter identifier is set to null.
               The contents of the line read from standard input is
               saved in the parameter REPLY.  The list is executed for
               each selection until a break or end-of-file is encoun-
               tered.

          case word in [ pattern [ | pattern ] ... ) list ;; ] ... esac
               A case command executes the list associated with the
               first pattern that matches word. The form of the pat-
               terns is the same as that used for file-name generation
               (see File Name Generation below).

     SH(1)                                                       SH(1)

          if list then list [ elif list then list ] ... [ else list ] fi
               The list following if is executed and, if it returns a
               zero exit status, the list following the first then is
               executed.  Otherwise, the list following elif is exe-
               cuted and, if its value is zero, the list following the
               next then is executed.  Failing that, the else list is
               executed.  If no else list or then list is executed,
               then the if command returns a zero exit status.

          while list do list done
          until list do list done
               A while command repeatedly executes the while list and,
               if the exit status of the last command in the list is
               zero, executes the do list; otherwise the loop termi-
               nates.  If no commands in the do list are executed,
               then the while command returns a zero exit status;
               until may be used in place of while to negate the loop
               termination test.

          (list)
               Execute list in a separate environment.  Note, that if
               two adjacent open parentheses are needed for nesting, a
               space must be inserted to avoid arithmetic evaluation
               as described below.

          { list;}
               list is simply executed.  Note that { is a keyword and
               requires a blank in order to be recognized.

          function identifier  { list ;}
          identifier  () { list ;}
               Define a function which is referenced by identifier.
               The body of the function is the list of commands
               between { and }.  (See Functions below).

          time pipeline
               The pipeline is executed and the elapsed time as well
               as the user and system time are printed on standard
               error.

          The following keywords are only recognized as the first word
          of a command and when not quoted:

          if then else elif fi case esac for while until do done { }
          function select time

        Comments.
          A word beginning with # causes that word and all the follow-
          ing characters up to a new-line to be ignored.

        Aliasing.
          The first word of each command is replaced by the text of an

     SH(1)                                                       SH(1)

          alias if an alias for this word has been defined.  The first
          character of an alias name can be any printable character,
          but the rest of the characters must be the same as for a
          valid identifier. The replacement string can contain any
          valid Shell script including the metacharacters listed
          above.  The first word of each command of the replaced text
          will not be tested for additional aliases.  If the last
          character of the alias value is a blank then the word fol-
          lowing the alias will also be checked for alias substitu-
          tion.  Aliases can be used to redefine special builtin com-
          mands but cannot be used to redefine the keywords listed
          above.  Aliases can be created, listed, and exported with
          the alias command and can be removed with the unalias com-
          mand.  Exported aliases remain in effect for sub-shells but
          must be reinitialized for separate invocations of the Shell
          (See Invocation below).

          Aliasing is performed when scripts are read, not while they
          are executed.  Therefore, for an alias to take effect the
          alias command has to be executed before the command which
          references the alias is read.

          Aliases are frequently used as a short hand for full path
          names.  An option to the aliasing facility allows the value
          of the alias to be automatically set to the full pathname of
          the corresponding command.  These aliases are called tracked
          aliases.  The value of a tracked alias is defined the first
          time the identifier is read and becomes undefined each time
          the PATH variable is reset.  These aliases remain tracked so
          that the next subsequent reference will redefine the value.
          Several tracked aliases are compiled into the shell.  The -h
          option of the set command makes each command name which is
          an identifier into a tracked alias.

          The following exported aliases are compiled into the shell
          but can be unset or redefined:
                              echo='print -'
                              false='let 0'
                              functions='typeset -f'
                              history='fc -l'
                              integer='typeset -i'
                              nohup='nohup '
                              pwd='print - $PWD'
                              r='fc -e -'
                              true=':'
                              type='whence -v'
                              hash='alias -t'

        Tilde Substitution.
          After alias substitution is performed, each word is checked
          to see if it begins with an unquoted ≈.  If it does, then
          the word up to a / is checked to see if it matches a user

     SH(1)                                                       SH(1)

          name in the /etc/passwd file.  If a match is found, the ≈
          and the matched login name is replaced by the login direc-
          tory of the matched user.  This is called a tilde substitu-
          tion.  If no match is found, the original text is left
          unchanged.  A ≈ by itself, or in front of a /, is replaced
          by the value of the HOME parameter.  A ≈ followed by a + or
          - is replaced by the value of the parameter PWD and OLDPWD
          respectively.

          In addition, the value of each keyword parameter is checked
          to see if it begins with a ≈ or if a ≈ appears after a :.
          In either of these cases a tilde substitution is attempted.

        Command Substitution.
          The standard output from a command enclosed in a pair of
          grave accents (``) may be used as part or all of a word;
          trailing new-lines are removed.  The command substitution
          `cat file` can be replaced by the equivalent but faster
          `<file`.  Command substitution of most special commands that
          do not perform input/output redirection are carried out
          without creating a separate process.

        Parameter Substitution.
          A parameter is an identifier, a digit, or any of the charac-
          ters *, @, #, ?, -, $, and !.  A named parameter (a parame-
          ter denoted by an identifier) has a value and zero or more
          attributes. Named parameters can be assigned values and
          attributes by using the typeset special command.  The
          attributes supported by the Shell are described later with
          the typeset special command.  Exported parameters pass val-
          ues and attributes to sub-shells but only values to the
          environment.

          The shell supports a limited one-dimensional array facility.
          An element of an array parameter is referenced by a
          subscript. A subscript is denoted by a [, followed by an
          arithmetic expression (see Arithmetic evaluation below) fol-
          lowed by a ].  The value of all subscripts must be in the
          range of 0 through 511.  Arrays need not be declared.  Any
          reference to a named parameter with a valid subscript is
          legal and an array will be created if necessary.  Referenc-
          ing an array without a subscript is equivalent to referenc-
          ing the first element.

          The value of a named parameter may also be assigned by writ-
          ing:

               name=value [ name=value ] ...

          If the integer attribute, -i, is set for name the value is
          subject to arithmetic evaluation as described below.
          Positional parameters, parameters denoted by a number, may

     SH(1)                                                       SH(1)

          be assigned values with the set special command.  Parameter
          $0 is set from argument zero when the shell is invoked.
          The character $ is used to introduce substitutable
          parameters.
          ${parameter}
               The value, if any, of the parameter is substituted.
               The braces are required when parameter is followed by a
               letter, digit, or underscore that is not to be inter-
               preted as part of its name or when a named parameter is
               subscripted.  If parameter is a digit then it is a
               positional parameter.  If parameter is * or @, then all
               the positional parameters, starting with $1, are sub-
               stituted (separated by spaces).  If an array identifier
               with subscript * or @ is used, then the value for each
               of the elements is substituted (separated by spaces).
          ${#parameter}
               If parameter is not *, the length of the value of the
               parameter is substituted.  Otherwise, the number of
               positional parameters is substituted.
          ${#identifier[*]}
               The number of elements in the array identifier is sub-
               stituted.
          ${parameter:-word}
               If parameter is set and is non-null then substitute its
               value; otherwise substitute word.
          ${parameter:=word}
               If parameter is not set or is null then set it to word;
               the value of the parameter is then substituted.  Posi-
               tional parameters may not be assigned to in this way.
          ${parameter:?word}
               If parameter is set and is non-null then substitute its
               value; otherwise, print word and exit from the shell.
               If word is omitted then a standard message is printed.
          ${parameter:+word}
               If parameter is set and is non-null then substitute
               word; otherwise substitute nothing.
          ${parameter#pattern}
          ${parameter##pattern}
               If the Shell pattern matches the beginning of the value
               of parameter, then the value of this substitution is
               the value of the parameter with the matched portion
               deleted; otherwise the value of this parameter is sub-
               stituted.  In the first form the smallest matching pat-
               tern is deleted and in the latter form the largest
               matching pattern is deleted.

          ${parameter%pattern}
          ${parameter%%pattern}
               If the Shell pattern matches the end of the value of
               parameter, then the value of parameter with the matched
               part deleted; otherwise substitute the value of
               parameter. In the first form the smallest matching

     SH(1)                                                       SH(1)

               pattern is deleted and in the latter form the largest
               matching pattern is deleted.

          In the above, word is not evaluated unless it is to be used
          as the substituted string, so that, in the following exam-
          ple, pwd is executed only if d is not set or is null:

               echo ${d:-`pwd`}

          If the colon ( : ) is omitted from the above expressions,
          then the shell only checks whether parameter is set or not.

          The following parameters are automatically set by the shell:
               #    The number of positional parameters in decimal.
               -    Flags supplied to the shell on invocation or by
                    the set command.
               ?    The decimal value returned by the last executed
                    command.
               $    The process number of this shell.
               _    The last argument of the previous command.  This
                    parameter is not set for commands which are asyn-
                    chronous.
               !    The process number of the last background command
                    invoked.
               PPID The process number of the parent of the shell.
               PWD  The present working directory set by the cd com-
                    mand.
               OLDPWD
                    The previous working directory set by the cd com-
                    mand.
               RANDOM
                    Each time this parameter is referenced, a random
                    integer is generated.  The sequence of random num-
                    bers can be initialized by assigning a numeric
                    value to RANDOM.
               REPLY
                    This parameter is set by the select statement and
                    by the read special command when no arguments are
                    supplied.

          The following parameters are used by the shell:
               CDPATH
                    The search path for the cd command.
               COLUMNS
                    If this variable is set, the value is used to
                    define the width of the edit window for the shell
                    edit modes and for printing select lists.
               EDITOR
                    If the value of this variable ends in emacs,
                    gmacs, or vi and the VISUAL variable is not set,
                    then the corresponding option (see Special Command
                    set below) will be turned on.

     SH(1)                                                       SH(1)

               ENV  If this parameter is set, then parameter substitu-
                    tion is performed on the value to generate the
                    pathname of the script that will be executed when
                    the shell is invoked.  (See Invocation below.)
                    This file is typically used for alias and function
                    definitions.
               FCEDIT
                    The default editor name for the fc command.
               IFS  Internal field separators, normally space, tab,
                    and new-line that is used to separate command
                    words which result from command or parameter sub-
                    stitution and for separating words with  the spe-
                    cial command read.
               HISTFILE
                    If this parameter is set when the shell is
                    invoked, then the value is the  pathname of the
                    file that will be used to store the command his-
                    tory.  (See Command re-entry below.)
               HISTSIZE
                    If this parameter is set when the shell is
                    invoked, then the number of previously entered
                    commands that are accessible by this shell will be
                    greater than or equal to this number.  The default
                    is 128.
               HOME The default argument (home directory) for the cd
                    command.
               MAIL If this parameter is set to the name of a mail
                    file and the MAILPATH parameter is not set, then
                    the shell informs the user of arrival of mail in
                    the specified file.
               MAILCHECK
                    This variable specifies how often (in seconds) the
                    shell will check for changes in the modification
                    time of any of the files specified by the MAILPATH
                    or MAIL parameters.  The default value is 600 sec-
                    onds.  If set to 0, the shell will check before
                    each prompt.
               MAILPATH
                    A colon ( : ) separated list of file names.  If
                    this parameter is set then the shell informs the
                    user of any modifications to the specified files
                    that have occurred within the last MAILCHECK sec-
                    onds.  Each file name can be followed by a ? and a
                    message that will be printed.  The message will
                    undergo parameter and command substitution with
                    the parameter, $_ defined as the name of the file
                    that has changed.  The default message is you have
                    mail in $_.
               PATH The search path for commands (see Execution
                    below).  The user may not change PATH if executing
                    under rsh (except in .profile ).
               PS1  The value of this parameter is expanded for

     SH(1)                                                       SH(1)

                    paramter substitution to define the primary prompt
                    string which by default is ``$ ''.  The character
                    ! in the primary prompt string is replaced by the
                    command number (see Command Re-entry below).
               PS2  Secondary prompt string, by default ``> ''.
               PS3  Selection prompt string used within a select loop,
                    by default ``#? ''.
               SHELL
                    The pathname of the shell is kept in the environ-
                    ment.  At invocation, if the value of this vari-
                    able contains an r in the basename, then the shell
                    becomes restricted.
               TMOUT
                    If set to a value greater than zero, the shell
                    will terminate if a command is not entered within
                    the prescribed number of seconds.  (Note that the
                    shell can be compiled with a maximum bound for
                    this value which cannot be exceeded.)
               VISUAL
                    If the value of this variable ends in emacs,
                    gmacs, or vi then the corresponding option (see
                    Special Command set below) will be turned on.

          The shell gives default values to PATH, PS1, PS2, MAILCHECK,
          TMOUT  and IFS, while HOME, SHELL ENV and MAIL are not set
          at all by the shell (although HOME is set by login(1)). On
          some systems MAIL and SHELL are also set by login(1)).

        Blank Interpretation.
          After parameter and command substitution, the results of
          substitutions are scanned for the field separator characters
          ( those found in IFS ) and split into distinct arguments
          where such characters are found.  Explicit null arguments
          ("" or ) are retained.  Implicit null arguments (those
          resulting from parameters that have no values) are removed.

        File Name Generation.
          Following substitution, each command word is scanned for the
          characters *, ?, and [ unless the -f option has been set.
          If one of these characters appears then the word is regarded
          as a pattern. The word is replaced with alphabetically
          sorted file names that match the pattern.  If no file name
          is found that matches the pattern, then the word is left
          unchanged.  When a pattern is used for file name generation,
          the character . at the start of a file name or immediately
          following a /, as well as the character / itself, must be
          matched explicitly.  In other instances of pattern matching
          the / and . are not treated specially.

               *    Matches any string, including the null string.
               ?    Matches any single character.
               [...]

     SH(1)                                                       SH(1)

                    Matches any one of the enclosed characters.  A
                    pair of characters separated by - matches any
                    character lexically between the pair, inclusive.
                    If the first character following the opening "[ "
                    is a "! " then any character not enclosed is
                    matched.  A - can be included in the character set
                    by putting it as the first or last character.

        Quoting.
          Each of the metacharacters listed above (See Definitions
          above).  has a special meaning to the shell and cause termi-
          nation of a word unless quoted.  A character may be quoted
          (i.e., made to stand for itself) by preceding it with a \.
          The pair \new-line is ignored.  All characters enclosed
          between a pair of single quote marks (''), except a single
          quote, are quoted.  Inside double quote marks (""), parame-
          ter and command substitution occurs and \ quotes the charac-
          ters \, ', ", and $.  "$*" is equivalent to "$1 $2 ...",
          whereas "$@" is equivalent to "$1" "$2" ....

          The special meaning of keywords can be removed by quoting
          any character of the keyword.  The recognition of special
          command names listed below cannot be altered by quoting
          them.

        Arithmetic Evaluation.
          An ability to perform integer arithmetic is provided with
          the special command let.  Evaluations are performed using
          long arithmetic.  Constants are of the form [base#]n where
          base is a decimal number between two and thirty-six repre-
          senting the arithmetic base and n is a number in that base.
          If base is omitted then base 10 is used.

          An internal integer representation of a named parameter can
          be specified with the -i option of the typeset special com-
          mand.  When this attribute is selected the first assignment
          to the parameter determines the arithmetic base to be used
          when parameter substitution occurs.

          Since many of the arithmetic operators require quoting, an
          alternative form of the let command is provided.  For any
          command which begins with a ((, all the characters until a
          matching )) are treated as a quoted expression.  More pre-
          cisely, (( ...  )) is equivalent to let " ...".

        Prompting.
          When used interactively, the shell prompts with the value of
          PS1 before reading a command.  If at any time a new-line is
          typed and further input is needed to complete a command,
          then the secondary prompt (i.e., the value of PS2) is
          issued.

     SH(1)                                                       SH(1)

        Input/Output.
          Before a command is executed, its input and output may be
          redirected using a special notation interpreted by the
          shell.  The following may appear anywhere in a simple-
          command or may precede or follow a command and are not
          passed on to the invoked command.  Command and parameter
          substitution occurs before word or digit is used except as
          noted below.  File name generation occurs only if the pat-
          tern matches a single file and blank interpretation is not
          performed.

          <word         Use file word as standard input (file descrip-
                        tor 0).

          >word         Use file word as standard output (file
                        descriptor 1).  If the file does not exist
                        then it is created; otherwise, it is truncated
                        to zero length.

          >>word        Use file word as standard output.  If the file
                        exists then output is appended to it (by first
                        seeking to the end-of-file); otherwise, the
                        file is created.

          <<[-]word     The shell input is read up to a line that is
                        the same as word, or to an end-of-file.  No
                        parameter substitution, command substitution
                        or file name generation is performed on word.
                        The resulting document, called a here-
                        document, becomes the standard input.  If any
                        character of word is quoted, then no interpre-
                        tation is placed upon the characters of the
                        document; otherwise, parameter and command
                        substitution occurs, \new-line is ignored, and
                        \ must be used to quote the characters \, $,
                        `, and the first character of word. If - is
                        appended to <<, then all leading tabs are
                        stripped from word and from the document.

          <&digit       The standard input is duplicated from file
                        descriptor digit (see dup(2)). Similarly for
                        the standard output using >& digit.

          <&-           The standard input is closed.  Similarly for
                        the standard output using >&-.

          If one of the above is preceded by a digit, then the file
          descriptor number referred to is that specified by the digit
          (instead of the default 0 or 1).  For example:

               ... 2>&1

     SH(1)                                                       SH(1)

          means file descriptor 2 is to be opened for writing as a
          duplicate of file descriptor 1.

          The order in which redirections are specified is signifi-
          cant.  The shell evaluates each redirection in terms of the
          (file descriptor, file) association at the time of evalua-
          tion.  For example:

               ... 1>fname 2>&1

          first associates file descriptor 1 with file fname. It then
          associates file descriptor 2 with the file associated with
          file descriptor 1 (i.e. fname). If the order of redirections
          were reversed, file descriptor 2 would be associated with
          the terminal (assuming file descriptor 1 had been) and then
          file descriptor 1 would be associated with file fname.

          If a command is followed by & and job control is not active,
          then the default standard input for the command is the empty
          file /dev/null.  Otherwise, the environment for the execu-
          tion of a command contains the file descriptors of the
          invoking shell as modified by input/output specifications.

        Environment.
          The environment (see environ(7)) is a list of name-value
          pairs that is passed to an executed program in the same way
          as a normal argument list.  The names must be identifiers
          and the values are character strings.  The shell interacts
          with the environment in several ways.  On invocation, the
          shell scans the environment and creates a parameter for each
          name found, giving it the corresponding value and marking it
          export . Executed commands inherit the environment.  If the
          user modifies the values of these parameters or creates new
          ones, using the export or typeset -x commands they become
          part of the environment.  The environment seen by any exe-
          cuted command is thus composed of any name-value pairs orig-
          inally inherited by the shell, whose values may be modified
          by the current shell, plus any additions which must be noted
          in export or typeset -x commands.

          The environment for any simple-command or function may be
          augmented by prefixing it with one or more parameter assign-
          ments.  A parameter assignment argument is a word of the
          form identifier=value. Thus:

               TERM=450 cmd args                  and
               (export TERM; TERM=450; cmd args)

          are equivalent (as far as the above execution of cmd is con-
          cerned).

          If the -k flag is set, all parameter assignment arguments

     SH(1)                                                       SH(1)

          are placed in the environment, even if they occur after the
          command name.  The following first prints a=b c and then c:

               echo a=b c
               set -k
               echo a=b c

        Functions.
          The function keyword, described in the Commands section
          above, is used to define shell functions.  Shell functions
          are read in and stored internally.  Alias names are resolved
          when the function is read.  Functions are executed like com-
          mands with the arguments passed as positional parameters.
          (See Execution below).

          Functions execute in the same process as the caller and
          share all files, traps ( other than EXIT and ERR) and pre-
          sent working directory with the caller.  A trap set on EXIT
          inside a function is executed after the function completes.
          Ordinarily, variables are shared between the calling program
          and the function.  However, the typeset special command used
          within a function defines local variables whose scope
          includes the current function and all functions it calls.

          The special command return is used to return from function
          calls.  Errors within functions return control to the
          caller.

          Function identifiers can be listed with the -f option of the
          typeset special command.  The text of functions will also be
          listed.  Function can be undefined with the -f option of the
          unset special command.

          Ordinarily, functions are unset when the shell executes a
          shell script.  The -xf option of the typeset command allows
          a function to be exported to scripts that are executed with-
          out a separate invocation of the shell.  Functions that need
          to be defined across separate invocations of the shell
          should be placed in the ENV file.

        Jobs.
          If the monitor option of the set command is turned on, an
          interactive shell associates a job with each pipeline.  It
          keeps a table of current jobs, printed by the jobs command,
          and assigns them small integer numbers.  When a job is
          started asynchronously with &, the shell prints a line which
          looks like:

               [1] 1234

          indicating that the job which was started asynchronously was
          job number 1 and had one (top-level) process, whose process

     SH(1)                                                       SH(1)

          id was 1234.

          This paragraph and the next require features that are not in
          all versions of UNIX and may not apply.  If you are running
          a job and wish to do something else you may hit the key ^Z
          (control-Z) which sends a STOP signal to the current job.
          The shell will then normally indicate that the job has been
          `Stopped', and print another prompt.  You can then manipu-
          late the state of this job, putting it in the background
          with the bg command, or run some other commands and then
          eventually bring the job back into the foreground with the
          foreground command fg.  A ^Z takes effect immediately and is
          like an interrupt in that pending output and unread input
          are discarded when it is typed.

          A job being run in the background will stop if it tries to
          read from the terminal.  Background jobs are normally
          allowed to produce output, but this can be disabled by giv-
          ing the command ``stty tostop''.  If you set this tty
          option, then background jobs will stop when they try to pro-
          duce output like they do when they try to read input.

          There are several ways to refer to jobs in the shell.  The
          character % introduces a job name.  If you wish to refer to
          job number 1, you can name it as %1 . Jobs can also be named
          by prefixes of the string typed in to kill or restart them.
          Thus, on systems that support job control, `fg %ed' would
          normally restart a suspended ed(1) job, if there were a sus-
          pended job whose name began with the string `ed'.

          The shell maintains a notion of the current and previous
          jobs.  In output pertaining to jobs, the current job is
          marked with a + and the previous job with a -.  The abbrevi-
          ation %+ refers to the current job and %- refers to the pre-
          vious job.  %% is also a synonym for the current job.

          This shell learns immediately whenever a process changes
          state.  It normally informs you whenever a job becomes
          blocked so that no further progress is possible, but only
          just before it prints a prompt.  This is done so that it
          does not otherwise disturb your work.

          When you try to leave the shell while jobs are running or
          stopped, you will be warned that `You have stopped(running)
          jobs.'  You may use the jobs command to see what they are.
          If you do this or immediately try to exit again, the shell
          will not warn you a second time, and the stopped jobs will
          be terminated.

        Signals.
          The INT and QUIT signals for an invoked command are ignored
          if the command is followed by & and job monitor option is

     SH(1)                                                       SH(1)

          not active.  Otherwise, signals have the values inherited by
          the shell from its parent, with the exception of signal 11
          (but see also the trap command below).

        Execution.
          Each time a command is executed, the above substitutions are
          carried out.  If the command name matches one of the Special
          Commands listed below, it is executed within the current
          shell process.  Next, the command name is checked to see if
          it matches one of the user defined functions.  If it does,
          the positional parameters are saved and then reset to the
          arguments of the function call.  When the function completes
          or issues a return, the positional parameter list is
          restored and any trap set on EXIT within the function is
          executed.  The value of a function is the value of the last
          command executed.  A function is also executed in the cur-
          rent shell process.  If a command name is not a special
          command or a user defined function, a process is created and
          an attempt is made to execute the command via exec(2).

          The shell parameter PATH defines the search path for the
          directory containing the command.  Alternative directory
          names are separated by a colon (:).  The default path is
          :/bin:/usr/bin (specifying the current directory, /bin, and
          /usr/bin, in that order).  Note that the current directory
          is specified by a null path name, which can appear immedi-
          ately after the equal sign, between colon delimiters, or at
          the end of the path list.  If the command name contains a /
          then the search path is not used.  Otherwise, each directory
          in the path is searched for an executable file.  If the file
          has execute permission but is not a directory or an a.out
          file, it is assumed to be a file containing shell commands.
          A sub-shell is spawned to read it.  All non-exported
          aliases, functions, and named parameters are removed in this
          case.  A parenthesized command is also executed in a sub-
          shell.

        Command Re-entry.
          The text of the last HISTSIZE (default 128) commands entered
          from a terminal device is saved in a history file.  The file
          $HOME/.history is used if the HISTFILE variable is not set
          or is not writable.  A shell can access the commands of all
          interactive shells which use the same named HISTFILE.  The
          special command fc is used to list or edit a portion this
          file.  The portion of the file to be edited or listed can be
          selected by number or by giving the first character or char-
          acters of the command.  A single command or range of com-
          mands can be specified.  If you do not specify an editor
          program as an argument to fc then the value of the parameter
          FCEDIT is used.  If FCEDIT is not defined then /bin/ed is
          used.  The edited command(s) is printed and re-executed upon
          leaving the editor.  The editor name - is used to skip the

     SH(1)                                                       SH(1)

          editing phase and to re-execute the command.  In this case a
          substitution parameter of the form old=new can be used to
          modify the command before execution.  For example, if r is
          aliased to 'fc -e -' then typing `r bad=good c' will re-
          execute the most recent command which starts with the letter
          c, replacing the string bad with the string good.

        In-line Editing Options
          Normally, each command line entered from a terminal device
          is simply typed followed by a new-line (`RETURN' or
          `LINE FEED').  If either the emacs, gmacs, or vi option is
          active, the user can edit the command line.  To be in either
          of these edit modes set the corresponding option.  An edit-
          ing option is automatically selected each time the VISUAL or
          EDITOR variable is assigned a value ending in either of
          these option names.

          The editing features require that the user's terminal accept
          `RETURN' as carriage return without line feed and that a
          space (` ' must overwrite the current character on the
          screen.  ADM terminal users should set the "space - advance"
          switch to `space'.  Hewlett-Packard series 2621 terminal
          users should set the straps to `bcGHxZ etX'.

          The editing modes implement a concept where the user is
          looking through a window at the current line.  The window
          width is the value of COLUMNS if it is defined, otherwise
          80.  If the line is longer than the window width minus two,
          a mark is displayed at the end of the window to notify the
          user.  As the cursor moves and reaches the window boundaries
          the window will be centered about the cursor.  The mark is a
          > ( <, *) if the line extends on the right (left, both)
          side(s) of the window.

        Emacs Editing Mode
          This mode is entered by enabling either the emacs or gmacs
          option.  The only difference between these two modes is the
          way they handle ^T.  To edit, the user moves the cursor to
          the point needing correction and then inserts or deletes
          characters or words as needed.  All the editing commands are
          control characters or escape sequences.  The notation for
          control characters is caret ( ^ ) followed by the character.
          For example, ^F is the notation for control F.  This is
          entered by depressing `f' while holding down the `CTRL'
          (control) key.  The `SHIFT' key is not depressed.  (The
          notation ^? indicates the DEL (delete) key.)

          The notation for escape sequences is M- followed by a char-
          acter.  For example, M-f (pronounced Meta f) is entered by
          depressing ESC (ascii 033 ) followed by `f'.  ( M-F would be
          the notation for ESC followed by `SHIFT' (capital) `F'.)

     SH(1)                                                       SH(1)

          All edit commands operate from any place on the line (not
          just at the beginning).  Neither the "RETURN" nor the "LINE
          FEED" key is entered after edit commands except when noted.

          ^F        Move cursor forward (right) one character.
          M-f       Move cursor forward one word.  (The editor's idea
                    of a word is a string of characters consisting of
                    only letters, digits and underscores.)
          ^B        Move cursor backward (left) one character.
          M-b       Move cursor backward one word.
          ^A        Move cursor to start of line.
          ^E        Move cursor to end of line.
          ^]char    Move cursor to character char on current line.
          ^X^X      Interchange the cursor and mark.
          erase     (User defined erase character as defined by the
                    stty command, usually ^H or #.)  Delete previous
                    character.
          ^D        Delete current character.
          M-d       Delete current word.
          M-^H      (Meta-backspace) Delete previous word.
          M-h       Delete previous word.
          M-^?      (Meta-DEL) Delete previous word (if your interrupt
                    character is ^? (DEL, the default) then this com-
                    mand will not work).
          ^T        Transpose current character with next character in
                    emacs mode.  Transpose two previous characters in
                    gmacs mode.
          ^C        Capitalize current character.
          M-C       Capitalize current word.
          ^K        Kill from the cursor to the end of the line.  If
                    given a parameter of zero then kill from the start
                    of line to the cursor.
          ^W        Kill from the cursor to the mark.
          M-p       Push the region from the cursor to the mark on the
                    stack.
          kill      (User defined kill character as defined by the
                    stty command, usually ^G or @.)  Kill the entire
                    current line.  If two kill characters are entered
                    in succession, all kill characters from then on
                    cause a line feed (useful when using paper termi-
                    nals).
          ^Y        Restore last item removed from line. (Yank item
                    back to the line.)
          ^L        Line feed and print current line.
          ^@        (Null character) Set mark.
          M-        (Meta space) Set mark.
          ^J        (New line)  Execute the current line.
          ^M        (Return)  Execute the current line.
          eof       End-of-file character, normally ^D, will terminate
                    the shell if the current line is null.
          ^P        Fetch previous command. Each time ^P is entered
                    the previous command back in time is accessed.

     SH(1)                                                       SH(1)

          M-<       Fetch the least recent (oldest) history line.
          M->       Fetch the most recent (youngest) history line.
          ^N        Fetch next command. Each time ^N is entered the
                    next command forward in time is accessed.
          ^Rstring  Reverse search history for a previous command line
                    containing string. If a parameter of zero is given
                    the search is forward.  String is terminated by a
                    "RETURN" or "NEW LINE".
          ^O        Operate - Execute the current line and fetch the
                    next line relative to current line from the his-
                    tory file.
          M-digits  (Escape) Define numeric parameter, the digits are
                    taken as a parameter to the next command.  The
                    commands that accept a parameter are ^F, ^B,
                    erase, ^D, ^K, ^R, ^P and ^N.
          M-letter  Soft-key - Your alias list is searched for an
                    alias by the name _letter and if an alias of this
                    name is defined, its value will be inserted on the
                    line.  The letter must not be one of the above
                    meta-functions.
          M-_       The last parameter of the previous command is
                    inserted on the line.
          M-.       The last parameter of the previous command is
                    inserted on the line.
          M-*       Attempt file name generation on the current word.
          ^U        Multiply parameter of next command by 4.
          \         Escape next character. Editing characters, the
                    user's erase, kill and interrupt (normally ^? )
                    characters may be entered in a command line or in
                    a search string if preceded by a \.  The \ removes
                    the next character's editing features (if any).
          ^V        Display version of the shell.

        Vi Editing Mode
          There are two typing modes.  Initially, when you enter a
          command you are in the input mode.  To edit, the user enters
          control mode by typing ESC ( 033 ) and moves the cursor to
          the point needing correction and then inserts or deletes
          characters or words as needed.  Most control commands accept
          an optional repeat count prior to the command.
          When in vi mode on most systems, canonical processing is
          initially enabled and the command will be echoed again if
          the speed is 1200 baud or greater and it contains any con-
          trol characters or less than one second has elapsed since
          the prompt was printed.  The ESC character terminates canon-
          ical processing for the remainder of the command and the
          user can than modify the command line.  This scheme has the
          advantages of canonical processing with the type-ahead echo-
          ing of raw mode.
          If the option viraw is also set, the terminal will always
          have canonical processing disabled.  This mode is implicit
          for systems that do not support two alternate end of line

     SH(1)                                                       SH(1)

          delimiters, and may be helpful for certain terminals.

             Input Edit Commands
               By default the editor is in input mode.
               erase     (User defined erase character as defined by
                         the stty command, usually ^H or #.)  Delete
                         previous character.
               ^W        Delete the previous blank separated word.
               ^D        Terminate the shell.
               ^V        Escape next character. Editing characters,
                         the user's erase or kill characters may be
                         entered in a command line or in a search
                         string if preceded by a ^V.  The ^V removes
                         the next character's editing features (if
                         any).
               \         Escape the next erase or kill character.

             Motion Edit Commands
               These commands will move the cursor.

               [count]l  Cursor forward (right) one character.

               [count]w  Cursor forward one alpha-numeric word.

               [count]W  Cursor to the beginning of the next word that
                         follows a blank.

               [count]e  Cursor to end of word.

               [count]E  Cursor to end of the current blank delimited
                         word.

               [count]h  Cursor backward (left) one character.

               [count]b  Cursor backward one word.

               [count]B  Cursor to preceding blank separated word.

               [count]fc Find the next character c in the current
                         line.

               [count]Fc Find the previous character c in the current
                         line.

               [count]tc Equivalent to f followed by h.

               [count]Tc Equivalent to F followed by l.

               ;         Repeats the last single character find com-
                         mand, f, F, t, or T.

               ,         Reverses the last single character find

     SH(1)                                                       SH(1)

                         command.

               0         Cursor to start of line.

               ^         Cursor to first non-blank character in line.

               $         Cursor to end of line.

             Search Edit Commands
               These commands access your command history.

               [count]k  Fetch previous command. Each time k is
                         entered the previous command back in time is
                         accessed.

               [count]-  Equivalent to k.

               [count]j  Fetch next command. Each time j is entered
                         the next command forward in time is accessed.

               [count]+  Equivalent to j.

               [count]G  The command number count is fetched.  The
                         default is the least recent history command.

               /string   Search backward through history for a previ-
                         ous command containing string. String is ter-
                         minated by a "RETURN" or "NEW LINE".  If
                         string is null the previous string will be
                         used.

               ?string   Same as / except that search will be in the
                         forward direction.

               n         Search for next match of the last pattern to
                         / or ? commands.

               N         Search for next match of the last pattern to
                         / or ?, but in reverse direction.  Search
                         history for the string entered by the previ-
                         ous / command.

             Text Modification Edit Commands
               These commands will modify the line.

               a         Enter input mode and enter text after the
                         current character.

               A         Append text to the end of the line.  Equiva-
                         lent to $a.

               [count]cmotion

     SH(1)                                                       SH(1)

               c[count]motion
                         Delete current character through the charac-
                         ter motion moves the cursor to and enter
                         input mode.  If motion is c, the entire line
                         will be deleted and input mode entered.

               C         Delete the current character through the end
                         of line and enter input mode.  Equivalent to
                         c$.

               S         Equivalent to cc.

               D         Delete the current character through the end
                         of line.

               [count]dmotion

               d[count]motion
                         Delete current character through the charac-
                         ter motion moves the cursor to.  Equivalent
                         to d$.  If motion is d , the entire line will
                         be deleted.

               i         Enter input mode and insert text before the
                         current character.

               I         Insert text before the beginning of the line.
                         Equivalent to the two character sequence ^i.

               [count]P  Place the previous text modification before
                         the cursor.

               [count]p  Place the previous text modification after
                         the cursor.

               R         Enter input mode and replace characters on
                         the screen with characters you type overlay
                         fashion.

               rc        Replace the current character with c.

               [count]x  Delete current character.

               [count]X  Delete preceding character.

               [count].  Repeat the previous text modification com-
                         mand.

               ≈         Invert the case of the current character and
                         advance the cursor.

               [count]_  Causes the count word of the previous command

     SH(1)                                                       SH(1)

                         to be appended and input mode entered.  The
                         last word is used if count is omitted.

               *         Causes an * to be appended to the current
                         word and file name generation attempted.  If
                         no match is found, it rings the bell.  Other-
                         wise, the word is replaced by the matching
                         pattern and input mode is entered.

             Other Edit Commands
               Miscellaneous commands.

               u         Undo the last text modifying command.

               U         Undo all the text modifying commands per-
                         formed on the line.

               [count]v  Returns the command fc -e
                         ${VISUAL:-${EDITOR:-vi}} count in the input
                         buffer.  If count is omitted, then the cur-
                         rent line is used.

               ^L        Line feed and print current line.  Has effect
                         only in control mode.

               ^J        (New line)  Execute the current line, regard-
                         less of mode.

               ^M        (Return)  Execute the current line, regard-
                         less of mode.

               #         Equivalent to I#<cr>.  Useful for causing the
                         current line to be inserted in the history
                         without being executed.

        Special Commands.
          The following simple-commands are executed in the shell pro-
          cess.  Input/Output redirection is permitted.  File descrip-
          tor 1 is the default output location.  Parameter assignment
          lists preceding the command do not remain in effect when the
          command completes unless noted.

          : [ arg ... ]
               Parameter assignments remain in effect after the com-
               mand completes.  The command only expands parameters.
               A zero exit code is returned.

     pletes.
          Parameter assignments remain in effect after the command com-
               Read and execute commands from file and return.  The
               commands are executed in the current Shell environment.
               The search path specified by PATH is used to find the

     SH(1)                                                       SH(1)

               directory containing file. If any arguments arg are
               given, they become the positional parameters.  Other-
               wise the positional parameters are unchanged.

          alias [ -tx ] [ name[ =value ]  ... ]
               Alias with no arguments prints the list of aliases in
               the form name=value on standard output.  An alias is
               defined for each name whose value is given.  A trailing
               space in value causes the next word to be checked for
               alias substitution.  The -t flag is used to set and
               list tracked aliases.  The value of a tracked alias is
               the full pathname corresponding to the given name. The
               value becomes undefined when the value of PATH is reset
               but the aliases remained tracked.  Without the -t flag,
               for each name in the argument list for which no value
               is given, the name and value of the alias is printed.
               The -x flag is used to set or print exported aliases.
               An exported alias is defined across sub-shell environ-
               ments.  Alias returns true unless a name is given for
               which no alias has been defined.

          bg [ %job ]
               This command is only built-in on systems that support
               job control.  Puts the specified job into the back-
               ground.  The current job is put in the background if
               job is not specified.

          break [ n ]
               Exit from the enclosing for while until or select loop,
               if any.  If n is specified then break n levels.

          continue [ n ]
               Resume the next iteration of the enclosing for while
               until or select loop.  If n is specified then resume at
               the n-th enclosing loop.

          cd [ arg ]
          cd  old new
               This command can be in either of two forms.  In the
               first form it changes the current directory to arg. If
               arg is - the directory is changed to the previous
               directory.  The shell parameter HOME is the default
               arg. The parameter PWD is set to the current directory.
               The shell parameter CDPATH defines the search path for
               the directory containing arg. Alternative directory
               names are separated by a colon (:).  The default path
               is <null> (specifying the current directory).  Note
               that the current directory is specified by a null path
               name, which can appear immediately after the equal sign
               or between the colon delimiters anywhere else in the
               path list.  If arg begins with a / then the search path
               is not used.  Otherwise, each directory in the path is

     SH(1)                                                       SH(1)

               searched for arg.
               The second form of cd substitutes the string new for
               the string old in the current directory name, PWD and
               tries to change to this new directory.
               The cd command may not be executed by rsh.

          eval [ arg ... ]
               The arguments are read as input to the shell and the
               resulting command(s) executed.

          exec [ arg ... ]
               Parameter assignments remain in effect after the com-
               mand completes.  If arg is given, the command specified
               by the arguments is executed in place of this shell
               without creating a new process.  Input/output arguments
               may appear and affect the current process.  If no argu-
               ments are given the effect of this command is to modify
               file descriptors as prescribed by the input/output
               redirection list.  In this case, any file descriptor
               numbers greater than 2 that are opened with this mecha-
               nism are closed when invoking another program.

          exit [ n ]
               Causes the shell to exit with the exit status specified
               by n. If n is omitted then the exit status is that of
               the last command executed.  An end-of-file will also
               cause the shell to exit except for a shell which has
               the ignoreeof option (See set below) turned on.

          export [ name ... ]
               The given names are marked for automatic export to the
               environment of subsequently-executed commands.

          fc [ -e ename  ] [ -nlr ] [ first ] [ last ]
          fc -e -  [ old=new ] [ command ]
               In the first form, a range of commands from first to
               last is selected from the last HISTSIZE commands that
               were typed at the terminal.  The arguments first and
               last may be specified as a number or as a string.  A
               string is used to locate the most recent command start-
               ing with the given string.  A negative number is used
               as an offset to the current command number.  If the
               flag -l, is selected, the commands are listed on stan-
               dard output.  Otherwise, the editor program ename is
               invoked on a file containing these keyboard commands.
               If ename is not supplied, then the value of the parame-
               ter FCEDIT (default /bin/ed) is used as the editor.
               When editing is complete, the edited command(s) is exe-
               cuted.  last is not specified then it will be set to
               first. If first is not specified the default is the
               previous command for editing and -16 for listing.  The
               flag -r reverses the order of the commands and the flag

     SH(1)                                                       SH(1)

               -n suppresses command numbers when listing.  In the
               second form the command is re-executed after the sub-
               stitution old=new is performed.

          fg [ %job ]
               This command is only built-in on systems that support
               job control.  If job is specified it brings it to the
               foreground.  Otherwise, the current job is brought into
               the foreground.

          jobs [ -l ]
               Lists the active jobs; given the -l options lists pro-
               cess id's in addition to the normal information.

          kill [ -sig ] process ...
               Sends either the TERM (terminate) signal or the speci-
               fied signal to the specified jobs or processes.  Sig-
               nals are either given by number or by names (as given
               in /usr/include/signal.h, stripped of the prefix
               ``SIG'').  The signal names are listed by kill -l'.
               There is no default, saying just `kill' does not send a
               signal to the current job.  If the signal being sent is
               TERM (terminate) or HUP (hangup), then the job or pro-
               cess will be sent a CONT (continue) signal if it is
               stopped.  The argument process can be either a process
               id or a job.

          let  arg ...
               Each arg is an arithmetic expression to be evaluated.
               All calculations are done as long integers and no check
               for overflow is performed.  Expressions consist of con-
               stants, named parameters, and operators.  The following
               set of operators, listed in order of decreasing prece-
               dence, have been implemented:
               -    unary minus
               !    logical negation
               *  /  %
                    multiplication, division, remainder
               +  - addition, subtraction
               <=  >=  <  >
                    comparison
               ==  !=
                    equality  inequality
               =    arithmetic replacement

               Sub-expressions in parentheses () are evaluated first
               and can be used to override the above precedence rules.
               The evaluation within a precedence group is from right
               to left for the = operator and from left to right for
               the others.

               A parameter name must be a valid identifier. When a

     SH(1)                                                       SH(1)

               parameter is encountered, the value associated with the
               parameter name is substituted and expression evaluation
               resumes.  Up to nine levels of recursion are permitted.

               The return code is 0 if the value of the last expres-
               sion is non-zero, and 1 otherwise.

          newgrp [ arg ... ]
               Equivalent to exec newgrp arg ....

          print [ -Rnprsu[n ]  ] [ arg ... ]
               The shell output mechanism.  With no flags or with flag
               -, the arguments are printed on standard output as
               described by echo(1). In raw mode, -R or -r, the escape
               conventions of echo are ignored.  The -R option will
               print all subsequent arguments and options other than
               -n.  The -p option causes the arguments to be written
               onto the pipe of the process spawned with |& instead of
               standard output.  The -s option causes the arguments to
               be written onto the history file instead of standard
               output.  The -u flag can be used to specify a one digit
               file descriptor unit number n on which the output will
               be placed.  The default is 1.  If the flag -n is used,
               no new-line is added to the output.

          read [ -prsu[ n ] ] [ name?prompt ] [ name ... ]
               The shell input mechanism.  One line is read and is
               broken up into words using the characters in IFS as
               separators.  In raw mode, -r, a \ at the end of a line
               does not signify line continuation.  The first word is
               assigned to the first name, the second word to the sec-
               ond name, etc., with leftover words assigned to the
               last name. The -p option causes the input line to be
               taken from the input pipe of a process spawned by the
               shell using |&.  If the -s fag is present, the input
               will be saved as a command in the history file.  The
               flag -u can be used to specify a one digit file
               descriptor unit to read from.  The file descriptor can
               be opened with the exec special command.  The default
               value of n is 0.  If name is omitted then REPLY is used
               as the default name. The return code is 0 unless an
               end-of-file is encountered.  An end-of-file with the -p
               option causes cleanup for this process so that another
               can be spawned.  If the first argument contains a ?,
               the remainder of this word is used as a prompt when the
               shell is interactive.  If the given file descriptor is
               open for writing and is a terminal device then the
               prompt is placed on this unit.  Otherwise the prompt is
               issued on file descriptor 2.  The return code is 0
               unless an end-of-file is encountered.

          readonly [ name ... ]

     SH(1)                                                       SH(1)

               The given names are marked readonly and these names
               cannot be changed by subsequent assignment.

          return [ n ]
               Causes a shell function to return to the invoking
               script with the return status specified by n. If n is
               omitted then the return status is that of the last com-
               mand executed.  If return is invoked while not in a
               function then it is the same as an exit.

          set [ -aefhkmnostuvx ] [ -o option ... ] [ arg ... ]
               The flags for this command have meaning as follows:
               -a      All subsequent parameters that are defined are
                       automatically exported.
               -e      If the shell is non-interactive and if a com-
                       mand fails, execute the ERR trap, if set, and
                       exit immediately.  This mode is disabled while
                       reading profiles.
               -f      Disables file name generation.
               -h      Each command whose name is an identifier
                       becomes a tracked alias when first encountered.
               -k      All parameter assignment arguments are placed
                       in the environment for a command, not just
                       those that precede the command name.
               -m      Background jobs will run in a separate process
                       group and a line will print upon completion.
                       The exit status of background jobs is reported
                       in a completion message.  On systems with job
                       control, this flag is turned on automatically
                       for interactive shells.
               -n      Read commands but do not execute them.
               -o      The following argument can be one of the fol-
                       lowing option names:
                       allexport
                               Same as -a.
                       errexit Same as -e.
                       emacs   Puts you in an emacs style in-line edi-
                               tor for command entry.
                       gmacs   Puts you in a gmacs style in-line edi-
                               tor for command entry.
                       ignoreeof
                               The shell will not exit on end-of-file.
                               The command exit must be used.
                       keyword Same as -k.
                       markdirs
                               All directory names resulting from file
                               name generation have a trailing /
                               appended.
                       monitor Same as -m.
                       noexec  Same as -n.
                       noglob  Same as -f.
                       nounset Same as -u.

     SH(1)                                                       SH(1)

                       verbose Same as -v.
                       trackall
                               Same as -h.
                       vi      Puts you in insert mode of a vi style
                               in-line editor until you hit escape
                               character 033.  This puts you in move
                               mode.  A return sends the line.
                       viraw   Each character is processed as it is
                               typed in vi mode.
                       xtrace  Same as -x.
                               If no option name is supplied then the current
                               option settings are printed.

               -s      Sort the positional parameters.
               -t      Exit after reading and executing one command.
               -u      Treat unset parameters as an error when substi-
                       tuting.
               -v      Print shell input lines as they are read.
               -x      Print commands and their arguments as they are
                       executed.
               -       Turns off -x and -v flags and stops examining
                       arguments for flags.
               --      Do not change any of the flags; useful in set-
                       ting $1 to a value beginning with -.  If no
                       arguments follow this flag then the positional
                       parameters are unset.

               Using + rather than - causes these flags to be turned
               off.  These flags can also be used upon invocation of
               the shell.  The current set of flags may be found in
               $-.  The remaining arguments are positional parameters
               and are assigned, in order, to $1, $2, ....  If no
               arguments are given then the values of all names are
               printed on the standard output.

          shift [ n ]
               The positional parameters from $n+1 ...  are renamed $1
               ...  , default n is 1.  The parameter n can be any
               arithmetic expression that evaluates to a non-negative
               number less than or equal to $#.

          test [ expr ]
               Evaluate conditional expression expr. See test(1) for
               usage and description.  The arithmetic comparison oper-
               ators are not restricted to integers.  They allow any
               arithmetic expression.  Four additional primitive
               expressions are allowed:
               -L file
                    True if file is a symbolic link.
               file1 -nt file2
                    True if file1 is newer than file2.
               file1 -ot file2

     SH(1)                                                       SH(1)

                    True if file1 is older than file2.
               file1 -ef file2
                    True if file1 has the same device and i-node num-
                    ber as file2.

          times
               Print the accumulated user and system times for the
               shell and for processes run from the shell.

          trap [ arg ] [ sig ] ...
               arg is a command to be read and executed when the shell
               receives signal(s) sig. (Note that arg is scanned once
               when the trap is set and once when the trap is taken.)
               Each sig can be given as a number or as the name of the
               signal.  Trap commands are executed in order of signal
               number.  Any attempt to set a trap on a signal that was
               ignored on entry to the current shell is ineffective.
               An attempt to trap on signal 11 (memory fault) produces
               an error.  If arg is omitted or is -, then all trap(s)
               sig are reset to their original values.  If arg is the
               null string then this signal is ignored by the shell
               and by the commands it invokes.  If sig is ERR then arg
               will be executed whenever a command has a non-zero exit
               code.  This trap is not inherited by functions.  If sig
               is 0 or EXIT and the trap statement is executed inside
               the body of a function, then the command arg is exe-
               cuted after the function completes.  If sig is 0 or
               EXIT for a trap set outside any function then the com-
               mand arg is executed on exit from the shell.  The trap
               command with no arguments prints a list of commands
               associated with each signal number.

          typeset [ -FLRZefilprtux[n ] [ name[ =value ]  ]  ... ]
               Parameter assignments remain in effect after the com-
               mand completes.  When invoked inside a function, a new
               instance of the parameter name is created.  The parame-
               ter value and type are restored when the function com-
               pletes.  The following list of attributes may be speci-
               fied:
               -F   This flag provides UNIX to host-name file mapping
                    on non-UNIX machines.
               -L   Left justify and remove leading blanks from value.
                    If n is non-zero it defines the width of the
                    field, otherwise it is determined by the width of
                    the value of first assignment.  When the parameter
                    is assigned to, it is filled on the right with
                    blanks or truncated, if necessary,  to fit into
                    the field.  Leading zeros are removed if the -Z
                    flag is also set.  The -R flag is turned off.
               -R   Right justify and fill with leading blanks.  If n
                    is non-zero it defines the width of the field,
                    otherwise it is determined by the width of the

     SH(1)                                                       SH(1)

                    value of first assignment.  The field is left
                    filled with blanks or truncated from the end if
                    the parameter is reassigned.  The L flag is turned
                    off.
               -Z   Right justify and fill with leading zeros if the
                    first non-blank character is a digit and the -L
                    flag has not been set.  If n is non-zero it
                    defines the width of the field, otherwise it is
                    determined by the width of the value of first
                    assignment.
               -e   Tag the parameter as having an error.  This tag is
                    currently unused by the shell and can be set or
                    cleared by the user.
               -f   The names refer to function names rather than
                    parameter names.  No assignments can be made and
                    the only other valid flag is -x.
               -i   Parameter is an integer.  This makes arithmetic
                    faster.  If n is non-zero it defines the output
                    arithmetic base, otherwise the first assignment
                    determines the output base.
               -l   All upper-case characters converted to lower-case.
                    The upper-case flag, -u is turned off.
               -p   The output of this command, if any,  is written
                    onto the two-way pipe
               -r   The given names are marked readonly and these
                    names cannot be changed by subsequent assignment.
               -t   Tags the named parameters.  Tags are user defin-
                    able and have no special meaning to the shell.
               -u   All lower-case characters are converted to upper-
                    case characters.  The lower-case flag, -l is
                    turned off.
               -x   The given names are marked for automatic export to
                    the environment of subsequently-executed commands.

               Using + rather than - causes these flags to be turned
               off.  If no name arguments are given but flags are
               specified, a list of names (and optionally the values )
               of the parameters which have these flags set is
               printed.  (Using + rather than - keeps the values to be
               printed.)  If no names and flags are given, the names
               and attributes of all parameters are printed.

          ulimit [ -cdfmpt ] [ n ]
               -c   imposes a size limit of n blocks on the size of
                    core dumps (BSD only).
               -d   imposes a size limit of n blocks on the size of
                    the data area (BSD only).
               -f   imposes a size limit of n blocks on files written
                    by child processes (files of any size may be
                    read).
               -m   imposes a soft limit of n blocks on the size of
                    physical memory (BSD only).

     SH(1)                                                       SH(1)

               -p   changes the pipe size to n (UNIX/RT only).
               -t   imposes a time limit of n seconds to be used by
                    each process (BSD only).

               If no option is given, -f is assumed.  If n is not
               given the current limit is printed.

          umask [ nnn ]
               The user file-creation mask is set to nnn (see
               umask(2)). If nnn is omitted, the current value of the
               mask is printed.

          unalias name ...
               The  parameters given by the list of names are removed
               from the alias list.

          unset [ -f ] name ...
               The parameters given by the list of names are unas-
               signed, i. e., their values and attributes are erased.
               Readonly variables cannot be unset.  If the flag, -f,
               is set, then the names refer to function names.

          wait [ n ]
               Wait for the specified process and report its termina-
               tion status.  If n is not given then all currently
               active child processes are waited for.  The return code
               from this command is that of the process waited for.

          whence [ -v ] name ...
               For each name, indicate how it would be interpreted if
               used as a command name.
               The flag, -v, produces a more verbose report.

        Invocation.
          If the shell is invoked by exec(2), and the first character
          of argument zero ($0) is -, then the shell is assumed to be
          a login shell and commands are read from /etc/profile and
          then from either .profile in the current directory or
          $HOME/.profile, if either file exists.  Next, commands are
          read from the file named by performing parameter substitu-
          tion on the value of the environment parameter ENV if the
          file exists.  Commands are then read as described below; the
          following flags are interpreted by the shell when it is
          invoked:

          -c string If the -c flag is present then commands are read
                    from string.
          -s        If the -s flag is present or if no arguments
                    remain then commands are read from the standard
                    input.  Shell output, except for the output of
                    some of the Special commands listed above, is
                    written to file descriptor 2.

     SH(1)                                                       SH(1)

          -i        If the -i flag is present or if the shell input
                    and output are attached to a terminal (as told by
                    gtty(2)) then this shell is interactive. In this
                    case TERMINATE is ignored (so that kill 0 does not
                    kill an interactive shell) and INTERRUPT is caught
                    and ignored (so that wait is interruptible).  In
                    all cases, QUIT is ignored by the shell.
          -r        If the -r flag is present the shell is a
                    restricted shell.

          The remaining flags and arguments are described under the
          set command above.

        Rsh Only.
          Rsh is used to set up login names and execution environments
          whose capabilities are more controlled than those of the
          standard shell.  The actions of rsh are identical to those
          of sh, except that the following are disallowed:
               changing directory (see cd(1)),
               setting the value of SHELL or PATH,
               specifying path or command names containing /,
               redirecting output (> and >>).

          The restrictions above are enforced after .profile and the
          ENV files are interpreted.

          When a command to be executed is found to be a shell proce-
          dure, rsh invokes sh to execute it.  Thus, it is possible to
          provide to the end-user shell procedures that have access to
          the full power of the standard shell, while imposing a lim-
          ited menu of commands; this scheme assumes that the end-user
          does not have write and execute permissions in the same
          directory.

          The net effect of these rules is that the writer of the
          .profile has complete control over user actions, by perform-
          ing guaranteed setup actions and leaving the user in an
          appropriate directory (probably not the login directory).

          The system administrator often sets up a directory of com-
          mands (i.e., /usr/rbin) that can be safely invoked by rsh.
          Some systems also provide a restricted editor red.

     EXIT STATUS
          Errors detected by the shell, such as syntax errors, cause
          the shell to return a non-zero exit status.  If the shell is
          being used non-interactively then execution of the shell
          file is abandoned.  Otherwise, the shell returns the exit
          status of the last command executed (see also the exit com-
          mand above).

     FILES

     SH(1)                                                       SH(1)

          /etc/passwd
          /etc/profile
          $HOME/.profile
          /tmp/sh*
          /dev/null

     SEE ALSO
          cat(1), cd(1), echo(1), emacs(1), env(1), gmacs(1), new-
          grp(1), test(1), umask(1), vi(1), dup(2), exec(2), fork(2),
          gtty(2), pipe(2), signal(2), umask(2), ulimit(2), wait(2),
          rand(3), a.out(5), profile(5), environ(7).

     CAVEATS
          If a command which is a tracked alias is executed, and then
          a command with the same name is installed in a directory in
          the search path before the directory where the original com-
          mand was found, the shell will continue to exec the original
          command.  Use the -t option of the alias command to correct
          this situation

          If you move the current directory or one above it, pwd may
          not give the correct response.  Use the cd command with a
          full path name to correct this situation.

          Some very old shell scripts contain a ^ as a synonym for the
          pipe character |.