Weird behavior using the read command in a infinite loop

Question

I have a script that checks if a file exists or not using the ls command. If there is not a file I ask the user if he would like to continue with the script.

What I am finding is that the read command excepts input from the terminal instead of the keyboard?

Here is my script:

function isfileThere(){
  output=$(ls ${1}  2>&1 >/dev/null)
  case $output in
    *"No such file or directory"*) 
      echo "DS not found: $output";
      option_exitprog; $output >> DSNotFound.txt ;;
    *) echo "DS found: $output";;
  esac
}

function option_exitprog(){
  while :
    do
    echo -n "Would you like to continue (y/n)?"
    read Answer
    #read -n1 -p "Would you like to continue (y/n)?"   Answer                                                                                                                                                                                                                 

    if [ ! -z "$Answer" ] ; then
        if [ "$Answer" == "y" ] ; then
            echo "Exiting script. Goodbye"
            exit 1
        elif [ "$Answer" == "n" ] ; then
            echo "Continue With Program"
            break
        else
            echo "We only accept (y/n)"
        fi
    else
        echo "You have entered a null string. We only accept (y/n)"
    fi
  done
}

function get_TotalEventEntries(){

cat<<EOF                                                                                                                                                                                                                                                                 

####################################                                                                                                                                                                                                                                      
#                                  #                                                                                                                                                                                                                                      
#                                  #                                                                                                                                                                                                                                      
#        get Total Entries         #                                                                                                                                                                                                                                      
#                                  #                                                                                                                                                                                                                                      
#                                  #                                                                                                                                                                                                                                      
####################################                                                                                                                                                                                                                                      

EOF                                                                                                                                                                                                                                                                           

  while read LINE
    do
    let total_DSNumber=total_DSNumber+1

    #Check if files exist                                                                                                                                                                                                                                                   
    isfileThere ${FileDir}/*${LINE}*/*.root*

    #print to file                                                                                                                                                                                                                                                          
    #printf "${LINE}="  >> ${Filename}                                                                                                                                                                                                                                      
    #getEntries ${LINE} >> ${Filename}                                                                                                                                                                                                                                      
  done < ${DSWildCardFile}

  echo "Finished running over $total_DSNumber file(s)"
}

get_TotalEventEntries

where is your var DSWildCardFile defined? Also, it may help if you edit your post to indicate what the expected behaviour is. Are you seeing any error messages? Do you mean accepts or expects (instead of excepts)? Have you tried debugging by adding set -vx near the top of your script? Good luck. — shellter
– shellter, Commented Feb 15, 2012 at 20:06
Ditto, the input of the while loop is whatever $DSWildCardFile expands to. — tripleee
– tripleee, Commented Feb 15, 2012 at 20:22
You should change your method of checking if a file exists. Use: if [[ -f $file ]]. In general, if you are using ls inside of a script, you are doing it wrong. — jordanm
– jordanm, Commented Feb 15, 2012 at 20:33
@jordanm yes that would be a better way. why do you have two test brackets? Always been confused by [[ ]] and (( )) ? — MWright
– MWright, Commented Feb 15, 2012 at 22:56
@MWright [[ is a bash shell feature that is similar to [, but more powerful and more likely to do what you expect. (( )) is for numerical context, and not limited to conditionals (eg. it can be used to increment a value ((count++)). The following link should help your understanding: mywiki.wooledge.org/BashGuide/TestsAndConditionals — jordanm
– jordanm, Commented Feb 16, 2012 at 17:15

jfg956 · Accepted Answer · 2012-02-15 20:23:43Z

2

The problem is at this line: done < ${DSWildCardFile}. You cannot read lines from this file and read user at the same time with read and simple redirection . To fix it, use more complex redirection and a new file descriptor:

while read -u 3 LINE
do
  ...
done 3< ${DSWildCardFile}

answered Feb 15, 2012 at 20:23

jfg956

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