How can I pass a file argument to my bash script using a Terminal command in Linux? [duplicate]

Question

So my question is how can I pass a file argument to my bash script using a Terminal command in Linux? At the moment I'm trying to make a program in bash that can take a file argument from the Terminal and use it as a variable in my program. For example I run myprogram --file=/path/to/file in Terminal.

My Program

#!/bin/bash     File=(the path from the argument)   externalprogram $File (other parameters) 

How can I achieve this with my program?

Answer 1

It'll be easier (and more "proper", see below) if you just run your script as

myprogram /path/to/file 

Then you can access the path within the script as $1 (for argument #1, similarly $2 is argument #2, etc.)

file="$1" externalprogram "$file" [other parameters] 

Or just

externalprogram "$1" [otherparameters] 

If you want to extract the path from something like --file=/path/to/file, that's usually done with the getopts shell function. But that's more complicated than just referencing $1, and besides, switches like --file= are intended to be optional. I'm guessing your script requires a file name to be provided, so it doesn't make sense to pass it in an option.

Answer 2

you can use getopt to handle parameters in your bash script. there are not many explanations for getopt out there. here is an example:

#!/bin/sh  OPTIONS=$(getopt -o hf:gb -l help,file:,foo,bar -- "$@")  if [ $? -ne 0 ]; then   echo "getopt error"   exit 1 fi  eval set -- $OPTIONS  while true; do   case "$1" in     -h|--help) HELP=1 ;;     -f|--file) FILE="$2" ; shift ;;     -g|--foo)  FOO=1 ;;     -b|--bar)  BAR=1 ;;     --)        shift ; break ;;     *)         echo "unknown option: $1" ; exit 1 ;;   esac   shift done  if [ $# -ne 0 ]; then   echo "unknown option(s): $@"   exit 1 fi  echo "help: $HELP" echo "file: $FILE" echo "foo: $FOO" echo "bar: $BAR" 

see also:

• the "canonical" example: http://software.frodo.looijaard.name/getopt/docs/getopt-parse.bash
• a blog post: http://www.missiondata.com/blog/system-administration/17/17/
• man getopt

links dead. here from internet archive:

• https://web.archive.org/web/20100325015445/http://software.frodo.looijaard.name/getopt/docs/getopt-parse.bash

• https://web.archive.org/web/20130827004301/http://www.missiondata.com/blog/system-administration/17/17/