How to get and compare Bash Function parameters?

Question

this should be a simple answer but I haven't been able to find a simple solution. I'm trying to create a bash script that runs the reindent.py tool scrip but I want to be able to get user input on whether or not he wants to write the file back to disk. Basically I want to type reindent_python -n FILE_PATH or reindent_python FILE_PATH. So far I got the following:

function reindent_python () {
    if ["$1" = "n"]; then
        ./reindent.py -n $2
    else
        ./reindent.py $2
    fi
}

Since this is my first shell script I'm not sure how to get whether or not the first parameter is -n and is $1 the n parameter and $2 the FILE_PATH? How would I got about creating this script?

Thank you!

exactly the same as `./reindent.py "$@"`, which expands the positional parameters — Diego Torres Milano, Mar 10 '17 at 20:29
@DiegoTorresMilano Sorry, I didn't understand your answer, would you mind explaining it? — Alexandre Krabbe, Mar 10 '17 at 20:31

damienfrancois · Accepted Answer · 2017-03-10T20:47:10.027

2

First off, what you display is a function, not a script. Your function could be as simple as:

function reindent_python () {
    ./reindent.py "$@"
}

given the fact that your Python script appear to take the same arguments as your function. You can simply pass them all to the Python script with the above construct.

As @CharlesDuffy mentions in the comment, the function keyword is not necessary:

reindent_python () {
    ./reindent.py "$@"
}

That aside, the if part should be

[ "$1" = "-n" ];

with a space around the brackets and a dash before the n.

edited Mar 10 '17 at 20:47

answered Mar 10 '17 at 20:32

damienfrancois

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I'd suggest removing the `function` keyword -- it makes the function incompatible with POSIX sh, whereas it would be entirely portable (and behave precisely the same) without it. – Charles Duffy Mar 10 '17 at 20:36

Chris Combs · Answer 2 · 2017-03-10T20:38:13.037

1

You're very close, just add the -. the string comparison is simplistic and does no other processing, it doesn't remove the hyphen for you.

function reindent_python () {
    if [ "$1" = "-n" ]; then
        ./reindent.py -n "$2"
    else
        ./reindent.py "$2"
    fi
}

or remove it when calling the function:

reindent_python n FILE_PATH

edited Mar 10 '17 at 20:38

answered Mar 10 '17 at 20:33

Chris Combs

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5
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Thank you for the suggestions @CharlesDuffy – Chris Combs Mar 10 '17 at 20:38

How to get and compare Bash Function parameters?

2 Answers2