BASH - Adding an argument that acts as a switch

Question

I'm currently working on a BASH script (unable to post as it's graded, however we are allowed to ask for GUIDANCE) and I've nearly completed it.

It uses the ls command a lot, and we need to make it so the user can choose whether or not they want the ls command to include human readable format of sizes or not. (i.e whether ls includes -h).

I was wondering, is there a way to make it so that if the second argument of the script execution is -h, that all ls commands will include the -h option?

Cheers!

man getopt is your answer

anubhava
– anubhava

2013-12-19 18:34:52 +00:00
Commented Dec 19, 2013 at 18:34 — anubhava
– anubhava, Commented Dec 19, 2013 at 18:34

that other guy · Accepted Answer · 2013-12-19 18:41:50Z

1

The most simplistic way of doing this is

#!/bin/bash
if [[ $1 == -h ]]
then
  flags="-h"
else
  flags=""
fi

ls -l $flags

You could then run

./yourscript -h
./yourscript

and it would run ls with and without -h respectively.

More robust solutions for parsing flags include getopts, which allow you to parse conventional Unix flag specifications like ./yourscript -e foo -d bar -vhq. If you want your script to allow more than this single argument, you should look into that.

answered Dec 19, 2013 at 18:41

that other guy

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1 Comment

JWyatt Over a year ago

So, say I had a .txt file with the following information in columns Size1 File1 Size2 File2 etc, How would I access the sizes, make them into human readable and replace all the sizes needed in the .txt file with the NEW sizes?

glenn jackman · Accepted Answer · 2013-12-19 18:37:03Z

0

If you're iterating over the results of ls, you need to read http://mywiki.wooledge.org/ParsingLs . If you're using ls just to display files, you're OK.

To do option parsing in your script, use the bash builtin getopts -- search for getopts here and I'm sure you find lots of examples.

answered Dec 19, 2013 at 18:37

glenn jackman

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Comments

michael501 · Accepted Answer · 2013-12-19 18:38:29Z

0

try something like :

human=${option+-$option}
ls $human
example :
option="h"
echo ls $human 
ls -h

answered Dec 19, 2013 at 18:38

michael501

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