Bash scripting; confused with for loop

Question

I need to make a for loop that loops for every item in a directory.

My issue is the for loop is not acting as I would expect it to.

  cd $1

  local leader=$2
  if [[ $dOpt = 0 ]]
  then
        local items=$(ls)
        local nitems=$(ls |grep -c ^)
  else
        local items=$(ls -l | egrep '^d' | awk '{print $9}')
        local nitems=$(ls -l | egrep '^d' | grep -c ^)
  fi

  for item in $items;
  do
     printf "${CYAN}$nitems\n${NONE}"
     let nitems--
     if [[ $nitems -lt 0 ]]
     then
          exit 4
     fi
     printf "${YELLOW}$item\n${NONE}"
  done

dOpt is just a switch for a script option.

The issue I'm having is the nitems count doesn't decrease at all, it's as if the for loop is only going in once. Is there something I'm missing?

Thanks

Try quoting your... let "nitems--", and also making items and nitems not local. — Mark Setchell
– Mark Setchell, Commented Apr 22, 2014 at 22:56
I do not see the point in grep -c ^. Try wc -l instead. Do you have filenames containing characters in $IFS? In general, use … | while read -r …; do …; done here instead. And try the built-in bash debugger. — PointedEars
– PointedEars, Commented Apr 22, 2014 at 23:05
grep -c ^ will count all the items in the directory, wc -l doesn't change anything. Also I changed $IFS to ":" at the beginning of the script. But thanks, I'll try making it a while loop instead of for loop. — JSarwer
– JSarwer, Commented Apr 22, 2014 at 23:09
I know what grep -c does; wc -l changes something in that it is more to the point, and probably more efficient as it does not need a regular expression engine. Looking forward to your results. — PointedEars
– PointedEars, Commented Apr 22, 2014 at 23:15

glenn jackman · Accepted Answer · 2014-04-23 00:03:57Z

3

Goodness gracious, don't rely on ls to iterate over files.
local is only useful in functions.
Use filename expansion patterns to store the filenames in an array.

  cd "$1"
  leader=$2             # where do you use this?

  if [[ $dOpt = 0 ]]
  then
      items=( * )
  else
      items=( */ )       # the trailing slash limits the results to directories
  fi
  nitems=${#items[@]}

  for item in "${items[@]}"     # ensure the quotes are present here
  do
      printf "${CYAN}$((nitems--))\n${NONE}"
      printf "${YELLOW}$item\n${NONE}"
  done

Using this technique will safely handle files with spaces, even newlines, in the name.

answered Apr 23, 2014 at 0:03

glenn jackman

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4 Comments

mklement0 Over a year ago

+1; shopt -s nullglob prior to globbing would deal with the case where no files/subfolders exist in the target folder.

JSarwer Over a year ago

Thanks a lot, very clean and elegant solution :)

user3520197 Over a year ago

Well, spaces will be handled as well in my script if you add IFS=$'\n' before the ls commands.

glenn jackman Over a year ago

@NotANumber, not with awk '{print $9}'

score 0 · Accepted Answer · 2014-04-22 23:36:46Z

0

Try this:

if [ "$dOpt" == "0" ]; then 
    list=(`ls`)
else
    list=(`ls -l | egrep '^d' | awk '{print $9}'`)
fi

for item in `echo $list`; do
    ... # do something with item
done

edited Apr 22, 2014 at 23:36

answered Apr 22, 2014 at 22:51

user3520197

3 Comments

PointedEars Over a year ago

This just does not work. It would iterate over what the command outputs that $mycmd expands to.

JSarwer Over a year ago

That didn't work. I don't understand what you're trying to do with that. you just changed the variable name when getting the items, but not in the for loop?

user3520197 Over a year ago

You are right... the command is wrong. I corrected it. Try now again please.

JSarwer · Accepted Answer · 2014-04-22 23:57:41Z

0

Thanks for all the suggestions. I found out the problem was changing $IFS to ":". While I meant for this to avoid problems with whitespaces in the filename, it just complicated things.

answered Apr 22, 2014 at 23:57

JSarwer

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