Introduction to the usage of getopts in shell

One 、getopts Command profile

getopts Command is used to parse Shell Tools for scripting command line parameters ,getopts Command parameters contain option characters that need to be recognized , If the option character is followed by a colon , Indicates that the character option requires a command line parameter （ The option characters and the corresponding command line parameters are separated by spaces ）（ Be careful ： The colon & Question marks cannot be used as option characters ）.getopts Every time a command is called , Put it in the next variable ,OPTARG Then you can get the parameter value ; If option Put a colon in front of it , It means ignoring the error

1.1 Command use format

getopts optstring name [arg...]

1. optstring List the corresponding Shell All parameters recognized by the script , for example ： Need to use -a,-f,-s When parameters are ,optstring yes afs; If necessary, the command line parameter is followed by a value , In the corresponding optstring Add a colon to the back , for example a:fs Express a There will be a value after the command line parameter , yes **-a value** In the form of ;
2. getopts If... Is matched during execution a Parameters , Will be able to -a Parameter corresponding value Stored in a place called OPTARG Of Shell Variable in ;
3. If optstring It starts with a colon , It indicates that when the command line appears optstring No error message will be prompted for parameters not in

Two 、 Example

stay Shell Script , For simple parameters , Often use $1,2 , . . . , n Just deal with it . But when there are too many command line parameters or we need to distinguish the use of command line parameters , You need to use getopts command

2.1

#!/bin/bash

func() {
    echo "Usage:"
    echo "test.sh [-j S_DIR] [-m D_DIR]"
    echo "Description:"
    echo "S_DIR,the path of source."
    echo "D_DIR,the path of destination."
    exit -1
}

upload="false"

while getopts 'h:j:m:u' OPT; do
    case $OPT in
        j) S_DIR="$OPTARG";;
        m) D_DIR="$OPTARG";;
        u) upload="true";;
        h) func;;
        ?) func;;
    esac
done

echo $S_DIR
echo $D_DIR
echo $upload

situation 1:

sh test.sh -j /data/usw/web -m /opt/data/web
## Output results 
/data/usw/web
/opt/data/web
false

situation 2:
getopts In the option character of the command , If you don't follow : The letter of is Switch type options , You do not need to specify a value , Equate to true/false, As long as you take this parameter with you, it's true. In the following example -u

getopts After the command recognizes each option , You can cooperate with case To operate . In operation , There are two " Constant ", One is OPTARG, To get the value of the current option ; The other is OPTIND, Express The displacement of the current option in the parameter list .case Of The last one is ?, Is used to identify illegal options , And carry out the corresponding operation , Our script outputs help information

sh test.sh -j /data/usw/web -m /opt/data/web -u
## Output results 
/data/usw/web
/opt/data/web
true

situation 3:

sh test.sh -h
## Output results 
test.sh: option requires an argument -- h
Usage:
test.sh [-j S_DIR] [-m D_DIR]
Description:
S_DIR,the path of source.
D_DIR,the path of destination.

situation 4:

sh test.sh j
## Output results 


false

2.2

#!/bin/bash

func() {
    echo "func:"
    echo "test.sh [-j S_DIR] [-m D_DIR]"
    echo "Description:"
    echo "S_DIR, the path of source."
    echo "D_DIR, the path of destination."
    exit -1
}

upload="false"

echo $OPTIND

while getopts 'j:m:u' OPT; do
    case $OPT in
        j) S_DIR="$OPTARG";;
        m) D_DIR="$OPTARG";;
        u) upload="true";;
        ?) func;;
    esac
done

echo $OPTIND
shift $(($OPTIND - 1))
echo $1

situation 1:

sh test.sh -j /data/usw/web beijing
## Output results 
1
3
beijing

situation 2:

sh test.sh -m /opt/data/web beijing
1
3
beijing

situation 3:

sh test.sh -j /data/usw/web -m /opt/data/web beijing
1
5
beijing

situation 4:

sh test.sh -j /data/usw/web -m /opt/data/web -u beijing
1
6
beijing