Difference between revisions of "How to use positional parameters"
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| − | == A Note About $@ and $* | + | == A Note About $@ and $* == |
| − | * $@ expanded as "$1" "$2" "$3" ... "$n" | + | * [[$@]] expanded as "$1" "$2" "$3" ... "$n" |
| − | * $* expanded as "$1y$2y$3y...$n", where y is the value of [[IFS|$IFS]] variable i.e. "$*" is one long string and $IFS act as an separator or token delimiters. | + | * [[$*]] expanded as "$1y$2y$3y...$n", where y is the value of [[IFS|$IFS]] variable i.e. "$*" is one long string and $IFS act as an separator or token delimiters. |
| + | === Example: The Difference Between $@ and $* === | ||
| + | Create a shell script called pizza.sh: | ||
| + | <source lang="bash">#!/bin/bash | ||
| + | IFS=", " | ||
| + | echo "* Displaying all pizza names using \$@" | ||
| + | echo "$@" | ||
| + | echo | ||
| + | |||
| + | echo "* Displaying all pizza names using \$*" | ||
| + | echo "$*"</source> | ||
| + | Save and close the file. Run it as follows: | ||
| + | <source lang="bash">chmod +x pizza.sh | ||
| + | ./pizza.sh Margherita Tomato Panner Gourmet</source> | ||
| + | Sample outputs: | ||
| + | <pre>* Displaying all pizza names using $@ | ||
| + | Margherita Tomato Panner Gourmet | ||
| + | |||
| + | *Displaying all pizza names using $* | ||
| + | Margherita,Tomato,Panner,Gourmet</pre> | ||
[[Category:Conditional Execution]][[Category:commands]] | [[Category:Conditional Execution]][[Category:commands]] | ||
Revision as of 22:37, 25 May 2010
← Shell command line parameters • Home • Parameters Set by the Shell →
All command line parameters ( positional parameters ) are available via special shell variable $1, $2, $3,...,$9.
How Do I Access Command-Line Arguments
Create a simple shell script called cmdargs.sh:
#!/bin/bash
echo "The script name : $0"
echo "The value of the first argument to the script : $1"
echo "The value of the second argument to the script : $2"
echo "The value of the third argument to the script : $3"
echo "The number of arguments passed to the script : $#"
echo "The value of all command-line arguments (\$* version) : $*"
echo "The value of all command-line arguments (\$@ version) : $@"
Save and close the file. Rut it as follows:
chmod +x cmdargs.sh
./cmdargs.sh bmw ford toyota
Sample outputs:
The script name : ./cmdargs.sh The value of the first argument to the script : bmw The value of the second argument to the script : ford The value of the third argument to the script : toyota The number of arguments passed to the script : 3 The value of all command-line arguments ($* version) : bmw ford toyota The value of all command-line arguments ($@ version) : bmw ford toyota
Try the following examples:
ls /tmp
./math 10 + 2
~/scripts/addzone cyberciti.com
~/scripts/adddomain cyberciti.biz '74.86.48.99' '2607:f0d0:1002:11::4'
/etc/init.d/named reload
/usr/local/etc/rc.d/jail restart cyberciti.biz
| Shell script name ($0) | Total number of arguments ($#) | Actual Command line argument ($1,..,$9) | ||
|---|---|---|---|---|
| ls | 1 | /tmp | ||
| ./math | 3 | 10, +, and 3 | ||
| ~/scripts/addzone | 1 | cyberciti.com | ||
| ~/scripts/adddomain | 3 | cyberciti.biz, 74.86.48.99, and 2607:f0d0:1002:11::4 | ||
| /etc/init.d/named reload | 1 | reload | ||
| /usr/local/etc/rc.d/jail | 2 | restart, and cyberciti.biz | ||
A Note About $@ and $*
- $@ expanded as "$1" "$2" "$3" ... "$n"
- $* expanded as "$1y$2y$3y...$n", where y is the value of $IFS variable i.e. "$*" is one long string and $IFS act as an separator or token delimiters.
Example: The Difference Between $@ and $*
Create a shell script called pizza.sh:
#!/bin/bash
IFS=", "
echo "* Displaying all pizza names using \$@"
echo "$@"
echo
echo "* Displaying all pizza names using \$*"
echo "$*"
Save and close the file. Run it as follows:
chmod +x pizza.sh
./pizza.sh Margherita Tomato Panner Gourmet
Sample outputs:
* Displaying all pizza names using $@ Margherita Tomato Panner Gourmet *Displaying all pizza names using $* Margherita,Tomato,Panner,Gourmet
← Shell command line parameters • Home • Parameters Set by the Shell →