Home / LinuxBash / I Wrote A Bash Function To Parse And Describe A Scripts Parameters
Overview
I am always skipping up and down in a bash script as I add script parameters and need to add a description for the parameter in the help_text / header.
I decided to write a function to generate the PARAMETER description from the parameter parsing case statement in the script. It uses the parameter case elements and comments within the case statement.
The Function
# Parses and prints script parameter details between two comments:
# "# Start Parse Script Parameters" and "# End Parse Script Parameters".
# Within the parameter parse case statement, parameters should be commented
# as follows:
#
# case $1 in
# -p|--param # <list> <parameters> <as a comment>
# # Desc: Describe the parameter in a comment starting "# Desc:"
# # Desc: For multiple lines, all mist start with "# Desc:"
# ...
# esac
function print_parameters() {
echo "PARAMETERS"
echo -e "$(cat $0 | sed -n '/^ *# Start Parse Script Parameters/,$p' \
| sed -n '/^ *# End Parse Script Parameters/q;p' \
| sed -n '/^ *-.*).*$/p; /^ *# Desc:/p' \
| sed 's/^ */ /; s/# Desc: */ /; s/\(^ *-.*\)) *$/\1/' \
| sed 's/\(^ *-.*\)) *# *\(.*\)/\n\\e[1m\1 \2\\e[0m/' \
| sed 's/\(^ *-.*\)/\n\\e[1m\1\\e[0m/') "
}
The Parameter Parsing case Statement
Note: The function parses the case statement between the two comments: # Start Parse Script Parameters and # End Parse Script Parameters.A
An example parameter parsing case statement.
# Start Parse Script Parameters
while [[ "$1" ]]; do
case $1 in
-h|--help)
# Desc: To show this help message.
echo "$help_text"
print_parameters
exit
;;
-e|--example) # <example-value>
# Desc: An example parameter.
# Desc: With a multi line description.
shift
username="$1"
;;
*)
echo "Error: Incorrect Parameter: $1"
errorYN=y
;;
esac
shift
done
# End Parse Script Parameters
The Output
Calling a script which contains the above function and the above parameter parsing case statement.
> example-script -h
NAME
example-script
USAGE
example-script
DESCRIPTION
An example script.
AUTHOR
mjnurse.dev - 2022
PARAMETERS
-h|--help
To show this help message.
-e|--example <example-value>
An example parameter.
With a multi line description.
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