Command line parameters are a way to pass information into a program or script in order for it to do what you want it to. Some examples of command line parameters:
ls -l cat textfileThe command line parameters here are the "-l" and "textfile"
How are command line parameters accessed within a shell script?
They are stored in these variables:
"$0":This holds the name of the command.
"$1":This holds the first parameter.
"$2":This holds the second parameter.
"$3":This holds the third parameter and the pattern repeats.
"$#":This holds the number of parameters that have been passed.
"$@":This holds all of the parameters
Lets make a simple script call it parameters.sh:
#!/bin/sh echo "Name of script:$0" echo "First parameter:$1" echo "Second parameter:$2" echo "Number of parameters:$#" echo "All parameters:$@"When we run the script you should get the following output
Input: sh parameters.sh hello world Output: Name of script:parameters.sh First parameter:hello Second parameter:world Number of parameters:2 All parameters:hello world