Getting the last argument passed to a shell script
ShellArgumentsShell Problem Overview
$1
is the first argument.
$@
is all of them.
How can I find the last argument passed to a shell script?
Shell Solutions
Solution 1 - Shell
This is Bash-only:
echo "${@: -1}"
Solution 2 - Shell
This is a bit of a hack:
for last; do true; done
echo $last
This one is also pretty portable (again, should work with bash, ksh and sh) and it doesn't shift the arguments, which could be nice.
It uses the fact that for
implicitly loops over the arguments if you don't tell it what to loop over, and the fact that for loop variables aren't scoped: they keep the last value they were set to.
Solution 3 - Shell
$ set quick brown fox jumps
$ echo ${*: -1:1} # last argument
jumps
$ echo ${*: -1} # or simply
jumps
$ echo ${*: -2:1} # next to last
fox
The space is necessary so that it doesn't get interpreted as a default value.
Note that this is bash-only.
Solution 4 - Shell
The simplest answer for bash 3.0 or greater is
_last=${!#} # *indirect reference* to the $# variable
# or
_last=$BASH_ARGV # official built-in (but takes more typing :)
That's it.
$ cat lastarg
#!/bin/bash
# echo the last arg given:
_last=${!#}
echo $_last
_last=$BASH_ARGV
echo $_last
for x; do
echo $x
done
Output is:
$ lastarg 1 2 3 4 "5 6 7"
5 6 7
5 6 7
1
2
3
4
5 6 7
Solution 5 - Shell
The following will work for you.
- @ is for array of arguments.
- : means at
- $# is the length of the array of arguments.
So the result is the last element:
${@:$#}
Example:
function afunction{
echo ${@:$#}
}
afunction -d -o local 50
#Outputs 50
Note that this is bash-only.
Solution 6 - Shell
Use indexing combined with length of:
echo ${@:${#@}}
Note that this is bash-only.
Solution 7 - Shell
Found this when looking to separate the last argument from all the previous one(s). Whilst some of the answers do get the last argument, they're not much help if you need all the other args as well. This works much better:
heads=${@:1:$#-1}
tail=${@:$#}
Note that this is bash-only.
Solution 8 - Shell
This works in all POSIX-compatible shells:
eval last=\${$#}
Source: http://www.faqs.org/faqs/unix-faq/faq/part2/section-12.html
Solution 9 - Shell
Here is mine solution:
- pretty portable (all POSIX sh, bash, ksh, zsh) should work
- does not shift original arguments (shifts a copy).
- does not use
evileval
- does not iterate through the whole list
- does not use external tools
Code:
ntharg() {
shift $1
printf '%s\n' "$1"
}
LAST_ARG=`ntharg $# "$@"`
Solution 10 - Shell
From oldest to newer solutions:
The most portable solution, even older sh
(works with spaces and glob characters) (no loop, faster):
eval printf "'%s\n'" "\"\${$#}\""
Since version 2.01 of bash
$ set -- The quick brown fox jumps over the lazy dog
$ printf '%s\n' "${!#} ${@:(-1)} ${@: -1} ${@:~0} ${!#}"
dog dog dog dog dog
For ksh, zsh and bash:
$ printf '%s\n' "${@: -1} ${@:~0}" # the space beetwen `:`
# and `-1` is a must.
dog dog
And for "next to last":
$ printf '%s\n' "${@:~1:1}"
lazy
Using printf to workaround any issues with arguments that start with a dash (like -n
).
For all shells and for older sh
(works with spaces and glob characters) is:
$ set -- The quick brown fox jumps over the lazy dog "the * last argument"
$ eval printf "'%s\n'" "\"\${$#}\""
The last * argument
Or, if you want to set a last
var:
$ eval last=\${$#}; printf '%s\n' "$last"
The last * argument
And for "next to last":
$ eval printf "'%s\n'" "\"\${$(($#-1))}\""
dog
Solution 11 - Shell
If you are using Bash >= 3.0
echo ${BASH_ARGV[0]}
Solution 12 - Shell
For bash
, this comment suggested the very elegant:
echo "${@:$#}"
To silence shellcheck
, use:
echo ${*:$#}
As a bonus, both also work in zsh
.
Solution 13 - Shell
shift `expr $# - 1`
echo "$1"
This shifts the arguments by the number of arguments minus 1, and returns the first (and only) remaining argument, which will be the last one.
I only tested in bash, but it should work in sh and ksh as well.
Solution 14 - Shell
I found @AgileZebra's answer (plus @starfry's comment) the most useful, but it sets heads
to a scalar. An array is probably more useful:
heads=( "${@: 1: $# - 1}" )
tail=${@:${#@}}
Note that this is bash-only.
Edit: Removed unnecessary $(( ))
according to @f-hauri's comment.
Solution 15 - Shell
If you want to do it in a non-destructive way, one way is to pass all the arguments to a function and return the last one:
#!/bin/bash
last() {
if [[ $# -ne 0 ]] ; then
shift $(expr $# - 1)
echo "$1"
#else
#do something when no arguments
fi
}
lastvar=$(last "$@")
echo $lastvar
echo "$@"
pax> ./qq.sh 1 2 3 a b
b
1 2 3 a b
If you don't actually care about keeping the other arguments, you don't need it in a function but I have a hard time thinking of a situation where you would never want to keep the other arguments unless they've already been processed, in which case I'd use the process/shift/process/shift/... method of sequentially processing them.
I'm assuming here that you want to keep them because you haven't followed the sequential method. This method also handles the case where there's no arguments, returning "". You could easily adjust that behavior by inserting the commented-out else
clause.
Solution 16 - Shell
A solution using eval
:
last=$(eval "echo \$$#")
echo $last
Solution 17 - Shell
For tcsh:
set X = `echo $* | awk -F " " '{print $NF}'`
somecommand "$X"
I'm quite sure this would be a portable solution, except for the assignment.
Solution 18 - Shell
After reading the answers above I wrote a Q&D shell script (should work on sh and bash) to run g++ on PGM.cpp to produce executable image PGM. It assumes that the last argument on the command line is the file name (.cpp is optional) and all other arguments are options.
#!/bin/sh
if [ $# -lt 1 ]
then
echo "Usage: `basename $0` [opt] pgm runs g++ to compile pgm[.cpp] into pgm"
exit 2
fi
OPT=
PGM=
# PGM is the last argument, all others are considered options
for F; do OPT="$OPT $PGM"; PGM=$F; done
DIR=`dirname $PGM`
PGM=`basename $PGM .cpp`
# put -o first so it can be overridden by -o specified in OPT
set -x
g++ -o $DIR/$PGM $OPT $DIR/$PGM.cpp
Solution 19 - Shell
The following will set LAST
to last argument without changing current environment:
LAST=$({
shift $(($#-1))
echo $1
})
echo $LAST
If other arguments are no longer needed and can be shifted it can be simplified to:
shift $(($#-1))
echo $1
For portability reasons following:
shift $(($#-1));
can be replaced with:
shift `expr $# - 1`
Replacing also $()
with backquotes we get:
LAST=`{
shift \`expr $# - 1\`
echo $1
}`
echo $LAST
Solution 20 - Shell
echo $argv[$#argv]
Now I just need to add some text because my answer was too short to post. I need to add more text to edit.
Solution 21 - Shell
This is part of my copy function:
eval echo $(echo '$'"$#")
To use in scripts, do this:
a=$(eval echo $(echo '$'"$#"))
Explanation (most nested first):
$(echo '$'"$#")
returns$[nr]
where[nr]
is the number of parameters. E.g. the string$123
(unexpanded).echo $123
returns the value of 123rd parameter, when evaluated.eval
just expands$123
to the value of the parameter, e.g.last_arg
. This is interpreted as a string and returned.
Works with Bash as of mid 2015.
Solution 22 - Shell
#! /bin/sh
next=$1
while [ -n "${next}" ] ; do
last=$next
shift
next=$1
done
echo $last
Solution 23 - Shell
Try the below script to find last argument
# cat arguments.sh
#!/bin/bash
if [ $# -eq 0 ]
then
echo "No Arguments supplied"
else
echo $* > .ags
sed -e 's/ /\n/g' .ags | tac | head -n1 > .ga
echo "Last Argument is: `cat .ga`"
fi
Output:
# ./arguments.sh
No Arguments supplied
# ./arguments.sh testing for the last argument value
Last Argument is: value
Thanks.
Solution 24 - Shell
There is a much more concise way to do this. Arguments to a bash script can be brought into an array, which makes dealing with the elements much simpler. The script below will always print the last argument passed to a script.
argArray=( "$@" ) # Add all script arguments to argArray
arrayLength=${#argArray[@]} # Get the length of the array
lastArg=$((arrayLength - 1)) # Arrays are zero based, so last arg is -1
echo ${argArray[$lastArg]}
Sample output
$ ./lastarg.sh 1 2 buckle my shoe
shoe
Solution 25 - Shell
Using parameter expansion (delete matched beginning):
args="$@"
last=${args##* }
It's also easy to get all before last:
prelast=${args% *}
Solution 26 - Shell
To return the last argument of the most recently used command use the special parameter:
$_
In this instance it will work if it is used within the script before another command has been invoked.
Solution 27 - Shell
$ echo "${*: -1}"
That will print the last argument
Solution 28 - Shell
With GNU bash
version >= 3.0:
num=$# # get number of arguments
echo "${!num}" # print last argument
Solution 29 - Shell
Just use !$
.
$ mkdir folder
$ cd !$ # will run: cd folder