parset - set shell variables in parallel
parset variablename [options for GNU Parallel]
env_parset variablename [options for GNU Parallel]
parset is a shell function that puts the output from GNU parallel into shell variables.
env_parset is a shell function that puts the output from env_parallel into shell variables.
The parset and env_parset functions are defined as part of env_parallel.
If variablename is a single variable name, this will be treated as the destination variable. If the variable is defined as an associative array (using typeset -A myassoc), this will be used. Otherwise the variable will be made into a normal array.
If variablename contains multiple names separated by ',' or space, the names will be the destination variables. The number of names must be at least the number of jobs.
Same as GNU parallel, but they are put after the destination variable.
Examples
Put output into myarray:
parset myarray seq 3 ::: 4 5 6 echo "${myarray[1]}"
Put output into vars $seq, $pwd, $ls:
parset "seq pwd ls" ::: "seq 10" pwd ls echo "$ls"
Put output into vars $seq, $pwd, $ls:
into_vars=(seq pwd ls) parset "${into_vars[*]}" ::: "seq 10" pwd ls echo "$ls"
Put output into associative array myassoc (not supported for mksh):
typeset -A myassoc parset myassoc seq ::: 4 5 ::: 6 7 echo "${myassoc[4 7]}"
The commands to run can be an array:
cmd=("echo first" "echo <<joe \"double space\" cartoon>>" "pwd") parset data ::: "${cmd[@]}" echo "${data[1]}" echo "${data[2]}"
parset can read from stdin (standard input) if it is a file:
parset res echo < parallel_input_file
but parset can not be part of a pipe. In particular this means it cannot read from a pipe or write to a pipe:
seq 10 | parset res echo Does not work
but must instead use a tempfile:
seq 10 > parallel_input parset res echo :::: parallel_input echo "${res[1]}" echo "${res[9]}"
or a FIFO:
mkfifo input_fifo seq 30 > input_fifo & parset res echo :::: input_fifo echo "${res[1]}" echo "${res[29]}"
or Bash/Zsh/Ksh process substitution:
parset res echo :::: <(seq 100) echo "${res[1]}" echo "${res[99]}"
Installation
Put this in the relevant $HOME/.bashrc or $HOME/.zshenv or $HOME/.kshrc:
. `which env_parallel.bash` . `which env_parallel.zsh` source `which env_parallel.ksh`
E.g. by doing:
echo . `which env_parallel.bash` >> $HOME/.bashrc echo . `which env_parallel.zsh` >> $HOME/.zshenv echo source `which env_parallel.ksh` >> $HOME/.kshrc
or by doing:
env_parallel --install
Examples
ash does not support arrays.
Put output into vars $seq, $pwd, $ls:
parset "seq pwd ls" ::: "seq 10" pwd ls echo "$ls"
parset can read from stdin (standard input) if it is a file:
parset res1,res2,res3 echo < parallel_input_file
but parset can not be part of a pipe. In particular this means it cannot read from a pipe or write to a pipe:
seq 3 | parset res1,res2,res3 echo Does not work
but must instead use a tempfile:
seq 3 > parallel_input parset res1,res2,res3 echo :::: parallel_input echo "$res1" echo "$res2" echo "$res3"
or a FIFO:
mkfifo input_fifo seq 3 > input_fifo & parset res1,res2,res3 echo :::: input_fifo echo "$res1" echo "$res2" echo "$res3"
Installation
Put the relevant one of these into $HOME/.profile:
. `which env_parallel.sh` . `which env_parallel.ash` . `which env_parallel.dash`
E.g. by doing:
echo . `which env_parallel.ash` >> $HOME/.bashrc
or by doing:
env_parallel --install
Same as GNU parallel.
When using GNU parallel for a publication please cite:
O. Tange (2011): GNU Parallel - The Command-Line Power Tool, ;login: The USENIX Magazine, February 2011:42-47.
Copyright (C) 2007-10-18 Ole Tange, http://ole.tange.dk
Copyright (C) 2008-2010 Ole Tange, http://ole.tange.dk
Copyright (C) 2010-2021 Ole Tange, http://ole.tange.dk and Free Software Foundation, Inc.
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parset uses GNU parallel.