Use Python's argparse module in shell scripts
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The function argparse parses its arguments using
argparse.ArgumentParser. The command line options are defined in
the function's stdin. argparse.bash should be in the same
directory as a script that uses it.
Python 2.7 or 3.5+ is required. See https://docs.python.org/2.7/library/argparse.html for a description of the python module. Note that some of the Python module's features won't work as expected (or at all) in this simplistic implementation.
Get argparse.bash
.. code-block:: shell
wget https://raw.githubusercontent.com/nhoffman/argparse-bash/master/argparse.bash chmod +x argparse.bash
Then move the file into the same directory as any scripts that will use it.
Alternatively, you can paste the body of the argparse() function
into your script (in which case you would of course omit the line
sourcing argparse.bash in the examples below).
Here's an example, example.sh
.. code-block:: bash
ARGPARSE_DESCRIPTION="Sample script description" # this is optional source $(dirname $0)/argparse.bash || exit 1 argparse "$@" <<EOF || exit 1 parser.add_argument('infile') parser.add_argument('outfile') parser.add_argument('-a', '--the-answer', default=42, type=int, help='Pick a number [default %(default)s]') parser.add_argument('-d', '--do-the-thing', action='store_true', default=False, help='store a boolean [default %(default)s]') parser.add_argument('-m', '--multiple', nargs='+', help='multiple values allowed') EOF
echo required infile: "$INFILE" echo required outfile: "$OUTFILE" echo the answer: "$THE_ANSWER" echo -n do the thing? if [[ $DO_THE_THING ]]; then echo " yes, do it" else echo " no, do not do it" fi echo -n "arg with multiple values: " for a in "${MULTIPLE[@]}"; do echo -n "[$a] " done echo
Example output of this script::
$ ./example.sh infile.txt "name with spaces.txt" required infile: infile.txt required outfile: name with spaces.txt the answer: 42 do the thing? no, do not do it arg with multiple values: []
Note that hyphens in the long option names are changed to underscores, and variables are all-caps (to be more bash-y).
Help text looks like this::
$ ./example.sh -h usage: example.sh [-h] [-a THE_ANSWER] [-d] [-m MULTIPLE [MULTIPLE ...]] infile outfile
Sample script description
positional arguments: infile outfile
optional arguments: -h, --help show this help message and exit -a THE_ANSWER, --the-answer THE_ANSWER Pick a number [default 42] -d, --do-the-thing store a boolean [default False] -m MULTIPLE [MULTIPLE ...], --multiple MULTIPLE [MULTIPLE ...] multiple values allowed
Error messages::
$ ./example.sh foo usage: example.sh [-h] [-a THE_ANSWER] [-d] [-m MULTIPLE [MULTIPLE ...]] infile outfile example.sh: error: too few arguments $ ./example.sh foo bar -n baz usage: example.sh [-h] [-a THE_ANSWER] [-d] [-m MULTIPLE [MULTIPLE ...]] infile outfile example.sh: error: unrecognized arguments: -n baz
Executing argparse.bash (as opposed to sourcing it) prints a
script template to stdout
.. code-block:: bash
$ ./argparse.bash
source $(dirname $0)/argparse.bash || exit 1 argparse "$@" <<EOF || exit 1 parser.add_argument('infile') parser.add_argument('-o', '--outfile')
EOF
echo "INFILE: ${INFILE}" echo "OUTFILE: ${OUTFILE}"
A few notes:
action=store_true or store_false provides a value of "yes"
for True, "" for Falseargs='+' or args='*' provides an array of values.MIT License (see LICENSE.txt)
Copyright (c) 2017 - 2022 Noah Hoffman