In Bash, how do you access command line arguments inside a function?

Question

I'm attempting to write a function in bash that will access the scripts command line arguments, but they are replaced with the positional arguments to the function. Is there any way for the function to access the command line arguments if they aren't passed in explicitly?

# Demo function
function stuff {
  echo $0 $*
}

# Echo's the name of the script, but no command line arguments
stuff

# Echo's everything I want, but trying to avoid
stuff $*

Answer 1

#!/usr/bin/env bash

echo name of script is $0
echo first argument is $1
echo second argument is $2
echo seventeenth argument is $17
echo number of arguments is $#

Edit: please see my comment on question

Answer 2

If you want to have your arguments C style (array of arguments + number of arguments) you can use $@ and $#.

$# gives you the number of arguments. $@ gives you all arguments. you can turn this into an array by args=("$@")

So for example:

args=("$@")
echo $# arguments passed
echo ${args[0]} ${args[1]} ${args[2]}

Note thate here ${args[0]} actually is the 1st argument and not the name of your script.

Answer 3

# Save the script arguments
SCRIPT_NAME=$0
ARG_1=$1
ARGS_ALL=$*

function stuff {
  # use script args via the variables you saved
  # or the function args via $
  echo $0 $*
} 


# Call the function with arguments
stuff 1 2 3 4

Answer 4

Ravi's comment is essentially the answer. Functions take their own arguments. If you want them to be the same as the command-line arguments, you must pass them in. Otherwise, you're clearly calling a function without arguments.

That said, you could if you like store the command-line arguments in a global array to use within other functions:

my_function() {
    echo "stored arguments:"
    for arg in "${commandline_args[@]}"; do
        echo "    $arg"
    done
}

commandline_args=("$@")

my_function

You have to access the command-line arguments through the commandline_args variable, not $@, $1, $2, etc., but they're available. I'm unaware of any way to assign directly to the argument array, but if someone knows one, please enlighten me!

Also, note the way I've used and quoted $@ - this is how you ensure special characters (whitespace) don't get mucked up.

Answer 5

My reading of the bash ref manual says this stuff is captured in BASH_ARGV, although it talks about "the stack" a lot.

#!/bin/bash

function argv {
    for a in ${BASH_ARGV[*]} ; do
      echo -n "$a "
    done
    echo
}

function f {
    echo f $1 $2 $3
    echo -n f ; argv
}

function g {
    echo g $1 $2 $3
    echo -n g; argv
    f
}

f boo bar baz
g goo gar gaz

Save in f.sh

$ ./f.sh arg0 arg1 arg2
f boo bar baz
farg2 arg1 arg0 
g goo gar gaz
garg2 arg1 arg0 
f
farg2 arg1 arg0