bash sed fail in while loop

Question

#!/bin/bash
fname=$2
rname=$1
echo \"$(<$fname)\" | while read line ; do
    result=`echo \"$(<$rname)\" | grep \"$line\"; echo $?`
    if [ $result != 0 ]
    the         


        

Answer 1

If I understand your need correctly, you want a file newaks which contains the lines in $fname which are also in $rname.

If this is what you want, using sed is overkill. Use fgrep:

fgrep -x -f $fname $rname > newkas

Also, there are problems with your script:

• you capture the output of grep in result, which means it will never be exactly 0; what you want is executing the command and simply check for $?
• your echoes are convoluted, just do grep whatever thefilename, or while...done ;
• finally, you take the line as is from the source file: the line can potentially be a regex, which means you will try and match a regex in $rname, which may yield to unexpected results.

And others.