Sstrhsrtj

I've got a shell script and I want to use the last argument:

#!/bin/bash

echo My last param is #somehow put it here

Here is what I've tried:

echo $$#

echo ${$#}

echo ${(($#))}

Unfortunately it did not work.

In a broader sense, I would like to know how to access the Nth argument from the end. How do I achieve that?

To get any argument, you can use slicing:

#!/bin/bash



# Get 3rd element from the end

from_end1=3

# Get last element

from_end2=1



# Get slice of array [end - from_end1 : end ] of length 1

echo "${@: -$from_end1: 1}"

echo "${@: -$from_end2: 1}"

You can also use this to get Nth element:

# Get 2nd element

from_beginning=2



echo "${@: $from_beginning: 1}"

Remember to check for length; this might return your program's name or an empty string.

In bash (release 4.3+), you may assign the passed parameters to an array and access the last one by the index -1:

#!/bin/bash



params=( "$@" )

printf 'The last parameter given to the script is %sn' "${params[-1]}"



foo () {

    params=( "$@" )

    printf 'The last parameter given to the function is %sn' "${params[-1]}"

}

In general, negative indexes into arrays accesses the elements from the end of the array.

In addition (to Kusalananda's answer):

#! /bin/bash 



echo "(bash/ksh): ${@: -1}"

echo "(bash 3.x+): ${!#}"

echo "(bash 3.x+): $BASH_ARGV"

echo "(bash 3.x+/ksh): ${@:$#}"

echo "(bash 3.x+): ${BASH_ARGV[0]}"

and if you worry about portability:

#!/bin/bash



penultimate=''

ultimate=''



for p in "$@" ; do

    penultimate="$ultimate"

    ultimate="$p"

done



echo "penultimate=$penultimate"

echo "ultimate=$ultimate"