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 and ghij  using a for loop and pass each value into a procedure    The script should allow extracting arbitrary number of comma-separated values from  variable

User · Accepted Answer

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".

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.

Hope this helps.

User · Answer

If you set a different field separator  you can directly use a for loop   IFS     for v in  variable do      things with   v      done   You can also store the values in an array and then loop through it as indicated in How do I split a string on a delimiter in Bash    IFS   read -ra values  lt  lt  lt    variable  for v in    values      do      things with   v  done   Test    variable  abc def ghij    IFS       for v in  variable  gt  do  gt  echo  var is  v   gt  done var is abc var is def var is ghij   You can find a broader approach in this solution to How to iterate through a comma-separated list and execute a command for each entry   Examples on the second approach     IFS   read -ra vals  lt  lt  lt   abc def ghij    printf   s n     vals      abc def ghij   for v in    vals       do echo   v --   done abc -- def -- ghij --

User · Answer

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

User · Answer

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

User · Answer

Here is an alternative tr based solution that doesn t use echo  expressed as a one-liner   for v in   tr       n   lt  lt  lt    var     do something with   v    done   It feels tidier without echo but that is just my personal preference

User · Answer

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

User · Answer

bin bash    TESTSTR  abc def ghij   for i in   echo  TESTSTR   tr       n   do echo  i done   I prefer to use tr instead of sed  becouse sed have problems with special chars like  r  n in some cases   other solution is to set IFS to certain separator

User · Answer

Another solution not using IFS and still preserving the spaces     var  a bc def ghij    while read line  do echo line   line   done  lt   lt  echo   var    tr       n   line a bc line def line ghij

[shell] Loop through a comma-separated shell variable

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