| title | date |
|---|---|
PARMAP(1) |
July 2020 |
parmap - parallelized execution of a shell command
parmap [option]... variable command
parmap reads arguments delimited by whitespace characters from standard input and invokes command in parallel for each argument. For each invocation, variable is set to the corresponding parsed argument and made available to command as an exported environment variable.
command should consist of a single quoted string to prevent shell expansions before execution. When invoked by parmap it will be interpreted by /bin/sh and hence should conform to valid POSIX shell syntax.
Delimiters for arguments read from standard input can be escaped using either a backslash or single/double quotes and can be changed with the commandline option -d.
Processing continues for each argument until one of three conditions:
- End of input
- A command invocation exits with a status of 255
- A command invocation is terminated by a signal
-d, --delimiter delim : Delimiter(s) for parsing standard input. A delimiter must be a 7-bit ascii character and cannot be the null byte. Multiple characters will be interpreted as separate delimiters. The default is whitespace characters.
-h, --help : Print help message and exit.
-m, --max-jobs number
: Maximum number of child processes to run in parallel. If unspecified
or set to less than or equal to zero, the default is the available
number of CPU cores as determined by _SC_NPROCESSORS_ONLN (see
sysconf(3)).
-v, --version : Print version number and exit.
If parmap encounters an internal error or if any of the child
processes return with a non-zero exit status or are terminated by a
signal, then parmap will exit with status 1. Otherwise, the exit
status will be 0 on success.
Simple example using default options:
# Output order may vary
$ echo 1 2 3 4 | parmap x 'echo number: $x'If using zsh, spaces in filenames can be escaped with quotes by using a glob modifier. For example:
$ touch "example file.txt"
$ print -r *(:q) | parmap f 'echo file: $f'find(1), xargs(1)