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prog - interface to running programs

bind '#p' /prog



The prog device serves a two-level structure. The first level contains numbered directories corresponding to pids of live Inferno processes. The second level, for each such directory, contains a set of files representing the corresponding process. All files operate on utf strings.

status (read-only)

The status file contains six fields, each separated by a blank. The fields are:
process identifiers

8 characters right justified

process group identifiers

8 characters right justified

user name

at least 10 characters left justified

process state

10 characters left justified

process memory

amount of memory used by the process in units of 1024 bytes with at least 5 characters, right justified, followed by a K

name of the current program module

up to 28 characters, left justified

pgrp (read-only)

The pgrp file contains the process group identifier in decimal format.

nsgrp (read-only)

The nsgrp file contains the name space group identifier in decimal format.

ns (read-only)

The ns file contains an ordered set of triples, separated by a space, which describe the bind and mount operations used to construct the name space. The fields are: the integer flags, the to file, and the from file.

wait (read-only)

The wait file may be read to recover information about the exiting children of the process. A read of wait will block until a child of the process, created after wait was opened, exits. When such a child exits, the read returns a string with three fields:
pid of exiting process

decimal value, followed by a space

module name

string, enclosed in double-quotes

error message

zero to 64 characters


Messages written to the ctl file control the execution of the process.

Kill the process.


Kill all processes in the same group as the process. A process writing to its own ctl file does not kill itself.


The dbgctl file provides facilities for debugging a process. Messages written to the file control the execution of the process.
step n

Step the interpreter for at most n instructions, or until a breakpoint is reached.


Step the interpreter until a return from the current activation frame or a breakpoint is reached.


Step the interpreter until a breakpoint is reached.


Run the process, ignoring any breakpoints.

bpt set pc path

Set a breakpoint at pc (program counter) for the module given by path.

bpt del pc path

Clear a breakpoint if one exists.

Reading dbgctl gives updates for some state transitions, while the process is being debugged. Each update is terminated by a newline, and includes the following messages:

The process exited without error.

broken: error

The process died due to error, a string with up to 64 characters.


The process is blocked sending on a channel.


The process is blocked receiving on a channel.


The process is blocked in an alt statement.


The process is unblocked and now ready to run.

new pid

The process has spawned a new process identified by pid.

stack (read-only)

The stack file contains the dynamic call stack trace. Each activation frame is described by one line with six fields, each separated by a space:
Frame pointer

8 hexadecimal digits

Program counter

8 hexadecimal digits

Module data pointer

8 hexadecimal digits

Module code pointer

8 hexadecimal digits

Execution method for the module

0 means interpreted, 1 compiled

The path name of the module

The top activation frame starts at offset 0.


The heap file may be queried to examine the state of the process. The file must be opened for both read and write (ORDWR). Moreover, access to this debugging facility may be not be allowed in production systems.

A data query contains an address, a period, a format character, and a count.

An instruction query contains a pc (program counter), a plus, a mode address, a period, the format I, and a count.

The addresses in the query may be decimal, hexadecimal preceded by 0x or 0X, or octal preceded by 0. Count gives the number of consecutive data items retrieved by reading heap starting at offset 0; the format varies according to the format character.

All data items other than strings are terminated by a newline.

32-bit decimal integers.


8-bit unsigned decimal bytes.


64-bit decimal integers.


64-bit reals.


Disassembled Dis instructions.


32-bit hexadecimal address, or nil.

The following formats examine properties of specific 32-bit pointers.

Examine a list, yielding a pair of hexadecimal addresses separated by a period, giving the address of the head and tail of a list. It is an error to use L on nil.


Examine an array, yielding a decimal length, a period, and the address of the 0th element of an array, or nil.


Examine a string, yielding the decimal length in characters, a period, and the utf representation of the string.


The text file is currently unimplemented.

process states

Inter-thread communication processing


Ready to transmit a value to another thread


Ready to receive a value from another thread




Available to execute instructions


Remove from queue to complete a kernel call


Thread instructions completed


Thread has crashed

See Also

ps - thread status in Chapter 5

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