how to create a loop in an if statement

Shell Programming and Scripting
1

Hey guys,

a=`cat abc | wc -l`
b=`cat def | wc -l`
 
if $a== $b
then
echo "a"
else 
echo "b"
fi

I want the if condition to retry itself , untill a==b.

I can't use goto statemt.
Please help.

Thanx in advance.

2
  1. use code tags
  2. wrap the conditional with while loop but this would never end ! If it matches, break... But it would never end if you dont try to change the content in else statement.
while true
do
    if [ $a == $b ]
    then
        echo "a"
        break
    else
        echo "b"
    fi
done
3

Hey,

I need to retry the if condition.

The count in a and b may vary with time.

So if he count of both the files is different, then my else condition will work.

I need the if condition to retry itself, until there is a change in count of a and b so that i reach the else condition.

4 
while true
do
    a=`wc -l <abc`
    b=`wc -l <def`

    if [ $a == $b ]
    then
        echo "a"
        break
    else
        echo "b"
        break
    fi
    sleep 5  # Sleep for 5 seconds before retry
done

Jean-Pierre.

5

Here's my 2 cents using ksh93 on Solaris:

#!/usr/dt/bin/dtksh

#Declare constants
typeset -r FILE1=abc
typeset -r FILE2=def

# Declare integer variables.
typeset -i a
typeset -i b

 # Loop forever (could be risky, but that was the requirement).
   while :
   do
    # Make sure both fles exist and have size.
    if [[ -s $FILE1 ]] && [[ -s $FILE2 ]]; then
      # Count lines in each file.
      a=$(wc -l < $FILE1)
      b=$(wc -l < $FILE2)

      if (( $a == $b )); then
        print "a"
        break
      else
        print "b"
        sleep 2
      fi
    else
      print "File $FILE1 or $FILE2 does not exist"
      exit 1
    fi
  done

exit 0
6

Its not workin aegsis.

I need retry the if condition and once the if condition is not satisfied i need to go to the else condtion and end the script.