Loop through a comma-separated shell variable

Question

Suppose I have a Unix shell variable as below

variable=abc,def,ghij

I want to extract all the values (abc, def an

Answer 1

Here's my pure bash solution that doesn't change IFS, and can take in a custom regex delimiter.

loop_custom_delimited() {
    local list=$1
    local delimiter=$2
    local item
    if [[ $delimiter != ' ' ]]; then
        list=$(echo $list | sed 's/ /'`echo -e "\010"`'/g' | sed -E "s/$delimiter/ /g")
    fi
    for item in $list; do
        item=$(echo $item | sed 's/'`echo -e "\010"`'/ /g')
        echo "$item"
    done
}

Answer 2

Try this one.

#/bin/bash   
testpid="abc,def,ghij" 
count=`echo $testpid | grep -o ',' | wc -l` # this is not a good way
count=`expr $count + 1` 
while [ $count -gt 0 ]  ; do
     echo $testpid | cut -d ',' -f $i
     count=`expr $count - 1 `
done

Answer 3

Another solution not using IFS and still preserving the spaces:

$ var="a bc,def,ghij"
$ while read line; do echo line="$line"; done < <(echo "$var" | tr ',' '\n')
line=a bc
line=def
line=ghij

Answer 4

Here is an alternative tr based solution that doesn't use echo, expressed as a one-liner.

for v in $(tr ',' '\n' <<< "$var") ; do something_with "$v" ; done

It feels tidier without echo but that is just my personal preference.

Answer 5

You can use the following script to dynamically traverse through your variable, no matter how many fields it has as long as it is only comma separated.

variable=abc,def,ghij
for i in $(echo $variable | sed "s/,/ /g")
do
    # call your procedure/other scripts here below
    echo "$i"
done

Instead of the echo "$i" call above, between the do and done inside the for loop, you can invoke your procedure proc "$i".

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Update: The above snippet works if the value of variable does not contain spaces. If you have such a requirement, please use one of the solutions that can change IFS and then parse your variable.

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Hope this helps.

Answer 6

Not messing with IFS
Not calling external command

variable=abc,def,ghij
for i in ${variable//,/ }
do
    # call your procedure/other scripts here below
    echo "$i"
done

Using bash string manipulation http://www.tldp.org/LDP/abs/html/string-manipulation.html