parmap

parmap is a commandline utility for executing in parallel a command for each argument read from standard input.

Installation

The target platform for parmap is x86_64 GNU/Linux; however, the code is fairly portable and the limited testsuite does pass when compiled against musl and on NetBSD/amd64.

To compile simply invoke make. There are no external dependencies.

$ make

# Optional, install in /usr/local
$ sudo make install

Building the debug target or invoking the integration tests with make test require GNU Make. If compiling on *BSD substitute make for gmake.

Usage

Basic usage consists of specifying a variable name to contain the parsed argument from standard input and a quoted shell command that may reference the specified variable.

For example, using the default delimiters of whitespace characters:

# Output order may vary
$ printf "1 2 3 4" | ./parmap x 'echo $(( $x + 1 ))'
2
3
4
5

Delimiters can be escaped using single/double quotes and backslashes. For example:

$ printf "'1 2' 3\ 4" | ./parmap x 'echo _$x'
_1 2
_3 4

The delimiter can be changed using the commandline option, -d. For example:

$ printf "1|2|3|4" | ./parmap -d '|' x 'echo _$x'
_1
_2
_3
_4

To limit the maximum number of parallel jobs use the commandline option, -m. For example:

# This will synchronously process the inputs from stdin by spawning
# at most 1 child process at a time.
$ printf "1 2 3 4" | ./parmap -m 1 x 'echo _$x'
_1
_2
_3
_4

For complete documentation refer to the provided manpage, parmap.1.

License

MIT