shell 之 getopt

格式一

getopt optstring parameters

# This is correct
getopt "hv:t::" "-v 123 -t123"  
getopt "hv:t::" "-v123 -t123"  # -v and 123 doesn't have whitespace

# -h takes no value.
getopt "hv:t::" "-h -v123"


# This is wrong. after -t can't have whitespace.
# Only optional params cannot have whitespace between key and value
getopt "hv:t::" "-v 123 -t 123"

# Multiple arguments that takes value.
getopt "h:v:t::g::" "-h abc -v 123 -t21"

# Multiple arguments without value
# All of these are correct
getopt "hvt" "-htv"
getopt "hvt" "-h -t -v"
getopt "hvt" "-tv -h"


Here h,v,t are the options and -h -v -t is how options should be given in command-line.
'h' is a no-value option. 無值的選項
'v:' implies that option -v has value and is a mandatory option. ':' means has a value. 帶值的選項
't::' implies that option -t has value but is optional. '::' means optional. 選項帶值可選

In optional param, value cannot have whitespace separation with the option. So, in "-t123" example, -t is option 123 is value.

這裏要特別注意，選項帶值可選時傳值的時候沒有空格!!!

格式二

getopt [getopt_options] [--] [optstring] [parameters]

The getopt_options, it describes how to parse the arguments. single dash long options, double dash options.
--, separates out the getopt_options from the options you want to parse and the allowed short options
The short options, is taken immediately after -- is found. Just like the Form first syntax.
The parameters, these are the options that you have passed into the program. The options you want to parse and get the actual values set on them.

example：
  getopt -l "name:,version::,verbose" -- "n:v::V" "--name=Karthik -version=5.2 -verbose"

說明參數支持的長形式和短形式。

格式三

getopt [getopt_options] [-o options] [--] [optstring] [parameters]

getopt -l "name:,version::,verbose" -a -o "n:v::V" -- "-name=Karthik -version=5.2 -verbose"

GETOPT_OPTIONS

getopt_options changes the way command-line params are parsed.
Below are some of the getopt_options.

-l, --longoptions:
參數名的長形式，用逗號隔開
getopt "name:,version" "--name=George"

-a, --alternative
允許長形式參數名只帶一個'-'
getopt "name:,version" "-name=George"

以下是一個來自網上的樣例

#!/bin/bash

# filename: commandLine.sh
# author: @theBuzzyCoder

showHelp() {
# `cat << EOF` This means that cat should stop reading when EOF is detected
cat << EOF  
Usage: ./installer -v <espo-version> [-hrV]
Install Pre-requisites for EspoCRM with docker in Development mode

-h, -help,          --help                  Display help

-v, -espo-version,  --espo-version          Set and Download specific version of EspoCRM

-r, -rebuild,       --rebuild               Rebuild php vendor directory using composer and compiled css using grunt

-V, -verbose,       --verbose               Run script in verbose mode. Will print out each step of execution.

EOF
# EOF is found above and hence cat command stops reading. This is equivalent to echo but much neater when printing out.
}


export version=0
export verbose=0
export rebuilt=0

# $@ is all command line parameters passed to the script.
# -o is for short options like -v
# -l is for long options with double dash like --version
# the comma separates different long options
# -a is for long options with single dash like -version
options=$(getopt -l "help,version:,verbose,rebuild,dryrun" -o "hv:Vrd" -a -- "$@")

# set --:
# If no arguments follow this option, then the positional parameters are unset. Otherwise, the positional parameters 
# are set to the arguments, even if some of them begin with a ‘-’.
eval set -- "$options"

while true
do
case $1 in
-h|--help) 
    showHelp
    exit 0
    ;;
-v|--version) 
    shift
    export version=$1
    ;;
-V|--verbose)
    export verbose=1
    set -xv  # Set xtrace and verbose mode.
    ;;
-r|--rebuild)
    export rebuild=1
    ;;
--)
    shift
    break;;
esac
shift
done

# With short options grouped together and long option
# With double dash '--version'
bash commandLine.sh --version=1.0 -rV

# With short options grouped together and long option
# With single dash '-version'
bash commandLine.sh -version=1.0 -rV

# OR with short option that takes value, value separated by whitespace by key
bash commandLine.sh -v 1.0 -rV

# OR with short option that takes value, value without whitespace separation from key.
bash commandLine.sh -v1.0 -rV

# OR Separating individual short options
bash commandLine.sh -v1.0 -r -V