argparse.bash

Use Python's argparse module in shell scripts

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 2.6+ or 3.2+ 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 (eg, nargs='+', boolean values) aren't going to work well (or at all) in this simplistic implementation.

Installation

Get argparse.bash:

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).

Usage

Here's an example, example.sh:

#!/bin/bash

source $(dirname $0)/argparse.bash
argparse "$@" <<EOF || exit 1
parser.add_argument('infile')
parser.add_argument('outfile')
parser.add_argument('-n', '--not-required', default=42, type=int,
                    help='optional argument [default %(default)s]')
EOF

echo required infile: "$INFILE"
echo required outfile: "$OUTFILE"
echo optional: "$NOT_REQUIRED"

Example output of this script:

$ ./example.sh infile.txt "name with spaces.txt"
required infile: infile.txt
required outfile: name with spaces.txt
optional: 42

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] [-n NOT_REQUIRED] infile outfile

positional arguments:
  infile
  outfile

optional arguments:
  -h, --help            show this help message and exit
  -n NOT_REQUIRED, --not-required NOT_REQUIRED
                        optional argument [default 42]

Error messages:

$ ./example.sh foo
usage: example.sh [-h] [-n NOT_REQUIRED] infile outfile
example.sh: error: too few arguments
$ ./example.sh foo bar -n baz
usage: example.sh [-h] [-n NOT_REQUIRED] infile outfile
example.sh: error: argument -n/--not-required: invalid int value: 'baz'

Executing argparse.bash (as opposed to sourcing it) prints a script template to stdout:

$ ./argparse.bash
#!/bin/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}"

License

MIT License (see LICENSE.txt)

Copyright (c) 2015 Noah Hoffman