proc
This section contains functions related to handling co-processes. The Bash builtin coproc is missing features, in particular there may be only one coproc open at any time.
This library comes with L_proc_popen which allows to open any number of child processes for writing and reading.
#!/bin/bash
. L_lib.sh
childs=()
for script in 'sleep 1 && exit 1' 'sleep 2; exit 2' 'sleep 3; exit 3'; do
L_proc_popen tmp bash -c "$script"
childs+=("$(L_array_to_string tmp)")
done
for i in "${childs[@]}"; do
L_array_from_string child "$i"
declare -p child
L_proc_wait child
echo "Child [$(L_proc_get_cmd child)] pid $(L_proc_get_pid child) exited with $(L_proc_get_exitcode child)"
done
Allows to open multiple processes connected via pipe.
Check if file descriptor is open.
Argument:
$1
file descriptor
Shellcheck disable= SC2188
Get free file descriptors
Argument:
$@
variables to assign with the file descriptor numbers
Open two connected file descriptors.
This intenrally creates a temporary file with mkfifo The result variable is assigned an array that: - [0] element is input from the pipe, - [1] element is the output to the pipe. This is meant to mimic the pipe() C function.
Arguments:
-
$1 <var>variable name to assign result to -
$2 <str>template temporary filename, default: L_pipe_XXXXXXXXXX
Shellcheck disable= SC2094
Process open. Coproc replacement.
The input/output options are in three groups:
- -I and -i for stdin,
- -O and -o for stdout,
- -E and -e for stderr.
Uppercase letter option specifies the mode for the file descriptor.
There are following modes available that you can give to uppercase options -I -O and -E:
- null - redirect to or from /dev/null
- close - close the file descriptor >&-
- input - -i specifies the string to forward to stdin. Only allowed for -I.
- stdout - connect file descriptor to stdout. -o or -e value are ignored.
- stderr - connect file descriptor to stderr. -o or -e value are ignored.
- pipe - create a fifo and connect file descriptor to it. -i -o or -e option specifies part of the temporary filename.
- file - connect file descriptor to file specified by -i -o or -e option
- fd - connect file descriptor to another file descriptor specified by -i -o or -e option
There first argument specifies an output variable that will be assigned as an array with the following indexes:
- [0] - if -Ipipe will store the file descriptor connected to stdin of the program, otherwise empty.
- [1] - if -Opipe will store the file descriptor connected to stdout of the program, otherwise empty.
- [2] - if -Epipe will store the file descriptor connected to stderr of the program, otherwise empty.
- [3] - stores the pid of the program.
- [4] - stores the generated command.
- [5] - stores exitcode.
You should use getters L_proc_get_* to extract the data from proc array elements.
Example
L_proc_popen -Ipipe -Opipe proc sed 's/w/W/g'
L_proc_printf proc "%s\n" "Hello world"
L_proc_read proc line
L_proc_wait -c -v exitcode proc
echo "$line"
echo "$exitcode"
Options:
-
-I <str>stdin mode -
-i <str>string for -Iinput, file for -Ifile, fd for -Ifd -
-O <str>stdout mode -
-o <str>file for -Ifile, fd for -Ifd -
-E <str>stderr mode -
-e <str>file for -Efile, fd for -Efd -
-p <int>Open a pipe for additional file descriptors. (TODO) -
-nDryrun mode. Do not execute the generated command. Instead print it to stdout.
Arguments:
-
$1variable name to store the result to. -
$@command to execute.
Get file descriptor for stdin of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Get file descriptor for stdout of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Get file descriptor for stderr of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Get PID of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Get command of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Get exitcode of L_proc.
Option:
-v <var>
variable to set
Argument:
$1
L_proc variable
Write printf formatted string to coproc.
Arguments:
-
$1L_proc variable -
$@any printf arguments
Exec read bultin with -u file descriptor of stdout of coproc.
Arguments:
-
$1L_proc variable -
$@any builtin read options
Exec read bultin with -u file descriptor of stderr of coproc.
Arguments:
-
$1L_proc variable -
$@any builtin read options
See: L_proc_read
Close stdin, stdout and stderr of L_proc
Argument:
$1
L_proc variable
Close stdin of L_proc.
Does nothing if already closed or not started with -Opipe.
Argument:
$1
L_proc variable
Close stdout of L_proc.
Does nothing if already closed or not started with -Opipe
Argument:
$1
L_proc variable
Close stderr of L_proc.
Does nothing if already closed or not started with -Epipe.
Argument:
$1
L_proc variable
Check if L_proc is finished.
Argument:
$1
L_proc variable
Exit: 0 if L_proc is running, 1 otherwise
Wait for L_proc to finish.
If L_proc has already finished execution, will only evaluate -v option.
Options:
-
-t <int>Timeout in seconds. Will try to use waitpid, tail --pid or busy loop with sleep. -
-v <var>Assign exitcode to this variable. -
-cClose L_proc file descriptors before waiting.
Argument:
$1
L_proc variable
Exit: 0 if L_proc has finished, 1 if timeout expired
Read from multiple file descriptors at the same time.
Arguments:
-
-t <timeout>Timeout in seconds. -
-p <timeout>Poll timeout. The read -t argument value. Default: 0.01 -
$1 <int>file descriptor to read from -
$2 <var>variable to assign the output of -
$@Pairs of variables and file descriptors.
Communicate with L_proc.
Options:
-
-i <str>Send string to stdin. -
-o <var>Assign stdout to this variable. -
-e <var>Assign stderr to this variable. -
-t <int>Timeout in seconds. -
-kKill L_proc after communication. -
-v <var>Assign exitcode to this variable.
Argument:
$1
L_proc variable
Exit: 0 on success. 2 on invalid options. 128 on timeout when reading output. 130 on timeout when waiting for process to terminate.
Send signal to L_proc.
Argument:
$1
L_proc variable
Terminate L_proc.
Argument:
$1
L_proc variable
Kill L_proc.
Argument:
$1
L_proc variable