Question

I know this has to be something simple, but I’m just not seeing it. We have a file, SpeakerList.txt, which contains a series of single lines of a speaker in our database. new.trs holds a space-delimited version of the database. I need to verify that we find the speaker in the database, so I’m running a grep for lines that start with the speaker name. The following code always results in the if statement at the end triggering for every speaker. I’ve got a similar bit of code that checks for file existence and it works just fine. What am I missing? I know that my grep loop is running — I’ve tried it with debug echo lines. I’ve also tried printing out the $speakerFound field and verified that it is indeed blank at the end, even when I have a statement showing that it was marked “found” earlier.

for i in `cat SpeakerList.txt`
do 
  speakerFound="" 
  echo "Speaker: $i"
  grep "^$i" ~/work/new.trs | while read line
  do 
    fileName=`echo $line | cut -d' ' -f 2`
    speakerFound="found"
    break
  done

  if [ "$speakerFound" == "" ]; then
    echo "$i not found in database."
  fi
done

Answer 1

You are setting your speakerFound variable in a subshell. Read this link for more details, but in general:

• When you redirect the stdin of a loop in bash, the loop will execute in a subshell.
• Because the loop is a subshell, variable assignments inside the loop will not be visible outside of the loop.

One solution is to use a file on disk to contain the result (write it in the inner loop, and read it back in when you need the result).