Bash: Passing parameters using getopts

Question

I know this is a simple question and I have been examining the getopts tutorials and examples, but I am stuck. If you check this link, you will see that with the help of @fedorqui, I have managed to write the code in order to get an element of an array in a file.

However, what I need is to parameterize the inputs so that the script will continue to work even if I change the order of inputs.

This is the first code I wrote:

#!/bin/bash

file=$3 row=$1 col=$2 str1="Hata: " str2=". satır " str3=". sütun yok"

if [ $row -gt 3 ]
then
    echo $str1$row$str2$col$str3
elif [ $col -gt 3 ]
then
    echo $str1$row$str2$col$str3
else
    awk 'NR==row{print $col}' row=$row col=$col $file
fi

Now, the script works like $ ./tablooku.sh 3 2 tablom.dat and the output is:

~/Desktop $ ./tablooku.sh 3 2 tablom.dat 
Kopenhag

What I need to do is to translate this code so that when I enter $ ./tablooku.sh -r 3 -c 2 tablom.dat, I get the script work.

This is the code I wrote which stucks upon running:

#!/bin/bash

str1="Hata: "
str2=". satır "
str3=". sütun yok"

while getopts "r:c:f:" opts
do
            case $opts in
            r)     row=$OPTARG echo "-r was triggered, Parameter: $OPTARG";;
            c)     col=$OPTARG echo "-c was triggered, Parameter: $OPTARG";;
            f)     fi=$OPTARG echo "-f was triggered, Parameter: $OPTARG";;
            \?)     printf "Kullanım: %s -r değer -c değer dosya adresi
" $0
                          exit 2;;
           esac
done

if [ $row -gt 3 ]
then
    echo $str1$row$str2$col$str3
elif [ $col -gt 3 ]
then
    echo $str1$row$str2$col$str3
else
    awk 'NR==r{print $c}' r=$row c=$col $fi
fi

Can you please tell me what is wrong here? When I run the command the system output is:

~/Desktop $ ./go_test.sh -r 3 -c 2 tablom.dat 
-r was triggered, Parameter: 3
-c was triggered, Parameter: 2
./go_test.sh: line 23: [: -gt: unary operator expected
./go_test.sh: line 26: [: -gt: unary operator expected

The prompt stucks and I have to use ctrl+z to break the waiting. It looks like I am failing to assign the file location to fi but I could not solve the problem

Note: Please remember -r is row, - c is column and the last parameter is the file location which does not use any option code (such as -f)

UPDATE 1:

I changed the if brackets ] with ]] and [ with [[. Now the unary operator expected error is gone. Now, the prompt waits and does not print -f was triggered, Parameter:... I still use ctrl+z to break the waiting.

UPDATE 2:

With the suggestion of both @grebneke and @TimK, I added the semi-colons and changed the fi parameter to fil. This way, I get the script working. However, there is one little problem remaining. The code works if I enter $ ./tablooku.sh -r 3 -c 2 -f tablom.dat. However, I need it to run without having to write -f. Is it possible?

grebneke · Accepted Answer

In these lines:

        r)     row=$OPTARG echo "-r was triggered, Parameter: $OPTARG";;
        c)     col=$OPTARG echo "-c was triggered, Parameter: $OPTARG";;
        f)     fi=$OPTARG echo "-f was triggered, Parameter: $OPTARG";;

You are assigning row/col/fi for the remainder of the line only. Add a semicolon after the assignment and it will stay assigned for the rest of the script:

        r)     row=$OPTARG; echo "-r was triggered, Parameter: $OPTARG";;
        c)     col=$OPTARG; echo "-c was triggered, Parameter: $OPTARG";;
        f)     fi=$OPTARG; echo "-f was triggered, Parameter: $OPTARG";;

Edit

Edit 2 To get the remaining arguments after using getopts, you must shift like this:

while getopts "r:c:" opts
do
...
done

shift $(( $OPTIND-1 ))

# Now, $1, $2 etc are your arguments as you are used to:
$ ./tablooku.sh -r 3 -c 2 tablom.dat
# $1 will be "tablom.dat"

Bash: Passing parameters using getopts

Answers (2)

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