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 · 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

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

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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

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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 --

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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

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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

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

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

[shell] Loop through a comma-separated shell variable

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