Shell shift procedure - What is this?
In shell we have the command shift, but i saw on some example its giving shift 3
Why there is a number after shift ? and what its about ? what it does ?
Example:
echo “arg1= $1 arg2=$2 arg3=$3”
shift
echo “arg1= $1 arg2=$2 arg3=$3”
shift
echo “arg1= $1 arg2=$2 arg3=$3”
shift
echo “arg1= $1 arg2=$2 arg3=$3”
shift
The output will be:
arg1= 1 arg2=2 arg3=3
arg1= 2 arg2=3 arg3=
arg1= 3 arg2= arg3=
arg1= arg2= arg3=
But when i add that, it doesn't display it correctly.
Answer
Take a look at the man page, which says:
shift [n]
The positional parameters from n+1 ... are renamed to $1 ....
If n is not given, it is assumed to be 1.
An Example script:
#!/bin/bash
echo "Input: $@"
shift 3
echo "After shift: $@"
Run it:
$ myscript.sh one two three four five six
Input: one two three four five six
After shift: four five six
This shows that after shifting by 3, $1=four, $2=five and $3=six.