{{{#!highlight sh
# Parallel copy
# Because we are copying the current directory, make sure $dst is correct
parallel --bar -j4 cp -avn -- "{}" "$dst" ::: *
# Old idea, much slower
find . -maxdepth 1 -mindepth 1 -print0 | parallel -q0 -j4 echo cp -avn "{}" "$dst"

# Check MP3s in parallel, many arguments per invocation
parallel -X mp3check -Sqe ::: *mp3
# Likewise, but recursively
find . -iname '*mp3' -print0 | parallel -0 -X mp3check -Sqe

# Run commands in a file parallel
parallel < commands.txt

# Using a file (one per line) of arguments
parallel 'some-command {}' ::: list-of-arguments.txt

# Parallel equivalent of
# `find $DIRECTORY -type f -exec sha1sum '{}' \; > $DIRECTORY.sha1`
find $DIRECTORY -type f -print0 | parallel -q0 -k sha1sum > $DIRECTORY.sha1

# Quickly get hash of large file. Reads in 1G chunks, multiple CPUs, and outputs 1 hash.
parallel --block=1G --pipepart -a $LARGE_FILE --progress --recend '' -k sha1sum | sha1sum
}}}

## useful options

 * `-X`: Multiple arguments per job, spread evenly across jobs, with context replace to replace "{}".
 * `-m`: Multiple arguments per job, spread evenly across jobs. Preferably use `-X`.
 * `--xargs`: Multiple arguments per job emulating xargs behavior; as many arguments per job as possible

 * `-n`: Limits number of arguments per job, use w/ `-X`, `--xargs`, or `-m`