[linux] How can I run a function from a script in command line?

I have a script that has some functions.

Can I run one of the function directly from command line?

Something like this?

myScript.sh func()

Using case

#!/bin/bash

fun1 () {
    echo "run function1"
    [[ "$@" ]] && echo "options: $@"
}

fun2 () {
    echo "run function2"
    [[ "$@" ]] && echo "options: $@"
}

case $1 in
    fun1) "$@"; exit;;
    fun2) "$@"; exit;;
esac

fun1
fun2

This script will run functions fun1 and fun2 but if you start it with option fun1 or fun2 it'll only run given function with args(if provided) and exit. Usage

$ ./test 
run function1
run function2

$ ./test fun2 a b c
run function2
options: a b c

Solved post but I'd like to mention my preferred solution. Namely, define a generic one-liner script eval_func.sh:

#!/bin/bash
source $1 && shift && "@a"

Then call any function within any script via:

./eval_func.sh <any script> <any function> <any args>...

An issue I ran into with the accepted solution is that when sourcing my function-containing script within another script, the arguments of the latter would be evaluated by the former, causing an error.

Edit: WARNING - seems this doesn't work in all cases, but works well on many public scripts.

If you have a bash script called "control" and inside it you have a function called "build":

function build() { 
  ... 
}

Then you can call it like this (from the directory where it is):

./control build

If it's inside another folder, that would make it:

another_folder/control build

If your file is called "control.sh", that would accordingly make the function callable like this:

./control.sh build

I have a situation where I need a function from bash script which must not be executed before (e.g. by source) and the problem with @$ is that myScript.sh is then run twice, it seems... So I've come up with the idea to get the function out with sed:

sed -n "/^func ()/,/^}/p" myScript.sh

And to execute it at the time I need it, I put it in a file and use source:

sed -n "/^func ()/,/^}/p" myScript.sh > func.sh; source func.sh; rm func.sh

Well, while the other answers are right - you can certainly do something else: if you have access to the bash script, you can modify it, and simply place at the end the special parameter "$@" - which will expand to the arguments of the command line you specify, and since it's "alone" the shell will try to call them verbatim; and here you could specify the function name as the first argument. Example:

$ cat test.sh
testA() {
  echo "TEST A $1";
}

testB() {
  echo "TEST B $2";
}

"$@"


$ bash test.sh
$ bash test.sh testA
TEST A 
$ bash test.sh testA arg1 arg2
TEST A arg1
$ bash test.sh testB arg1 arg2
TEST B arg2

For polish, you can first verify that the command exists and is a function:

# Check if the function exists (bash specific)
if declare -f "$1" > /dev/null
then
  # call arguments verbatim
  "$@"
else
  # Show a helpful error
  echo "'$1' is not a known function name" >&2
  exit 1
fi

Briefly, no.

You can import all of the functions in the script into your environment with source (help source for details), which will then allow you to call them. This also has the effect of executing the script, so take care.

There is no way to call a function from a shell script as if it were a shared library.

you can call function from command line argument like below

function irfan() {
echo "Irfan khan"
date
hostname
}
function config() {
ifconfig
echo "hey"
}
$1

once you function end put $1 to accept argument let say above code is saved in fun.sh to run function ./fun.sh irfan & ./fun.sh config

The following command first registers the function in the context, then calls it:

. ./myScript.sh && function_name