CODEWITHSUNDEEP
bashcommand-line-argumentsargv
DonGar
DonGar

Reputation: 7644

How to access command line arguments of the caller inside a function?

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 $*

Upvotes: 130

Views: 205068

Answers (10)

eNca
eNca

Reputation: 1275

This is @mcarifio response with several comments incorporated:

#!/bin/bash

shopt -s extdebug

function stuff() {
  local argIndex="${#BASH_ARGV[@]}"
  while [[ argIndex -gt 0 ]] ; do
    argIndex=$((argIndex - 1))
    echo -n "${BASH_ARGV[$argIndex]} "
  done
  echo
}

stuff

I want to highlight:

Upvotes: 2

cabonamigo
cabonamigo

Reputation: 11

I do it like this:

#! /bin/bash

ORIGARGS="$@"

function init(){   
  ORIGOPT= "- $ORIGARGS -" # tacs are for sed -E 
  echo "$ORIGOPT"
}

Upvotes: 1

JamesIsIn
JamesIsIn

Reputation: 296

The simplest and likely the best way to get arguments passed from the command line to a particular function is to include the arguments directly in the function call.

# first you define your function 
function func_ImportantPrints() {
    printf '%s\n' "$1" 
    printf '%s\n' "$2" 
    printf '%s\n' "$3" 
} 
# then when you make your function call you do this:  
func_ImportantPrints "$@"

This is useful no matter if you are sending the arguments to main or some function like func_parseArguments (a function containing a case statement as seen in previous examples) or any function in the script.

Upvotes: 0

mcarifio
mcarifio

Reputation: 891

My reading of the Bash Reference Manual says this stuff is captured in BASH_ARGV, although it talks about "the stack" a lot.

#!/bin/bash

shopt -s extdebug

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
fbaz bar boo arg2 arg1 arg0
g goo gar gaz
ggaz gar goo arg2 arg1 arg0
f
fgaz gar goo arg2 arg1 arg0

Upvotes: 57

Marin Alcaraz
Marin Alcaraz

Reputation: 19

You can use the shift keyword (operator?) to iterate through them. Example:

#!/bin/bash
function print()
{
    while [ $# -gt 0 ]
    do
        echo "$1"
        shift 1
    done
}
print "$@"

Upvotes: 1

stigi
stigi

Reputation: 6711

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

Upvotes: 121

Vikash Singh
Vikash Singh

Reputation: 910

One can do it like this as well

#!/bin/bash
# script_name function_test.sh
function argument(){
for i in $@;do
    echo $i
done;
}
argument $@

Now call your script like

./function_test.sh argument1 argument2

Upvotes: 3

Cascabel
Cascabel

Reputation: 496852

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.

Upvotes: 23

Peter Coulton
Peter Coulton

Reputation: 55789

# 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

Upvotes: 7

Ravi Vyas
Ravi Vyas

Reputation: 12375

#!/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

Upvotes: 28

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