skip lines while reading a file

Shell Programming and Scripting
1

Hi Experts,

I am tryin to read a file and while doing so i need to skip the lines which start with a hash (#) char.

I thought of using a goto command but a lot of guys on this site say its not the good way to program. Moreover I am using a ksh shell which deos not support goto command.

Below is the algo I am using; which definately doesn't work. I need a logic to substitute GOTO command. I have thought of using case logic and also functions; but they some how dont fit well with the work I am trying to do. Let me know if you need more details/info

Please advise guys.

Thanks in advance. :b:

 
cat <file name> | while read i
do 
      if [[ <hash char enountered> ]]; then
       goto end_of_pgm
      fi
etc 
etc
etc
end_of_pgm
   echo $i
done
2

Even though you are saying that you want to skip lines that start with "#", at the same time you say that you want to quit when you see it.

If you want to skip "#":

!/usr/bin/ksh
egrep -v '^#' inp_file |
while read mLine
do
  echo "mLine = <${mLine}>"
done

If you want to quit when "#" appears:

!/usr/bin/ksh
sed -n '/^#/q;p' inp_file |
while read mLine
do
  echo "mLine = <${mLine}>"
done
1 Like
3

Thanks for your reply.
Sorry if I was not clear. Its not that i want to quit i want to skip that particular line and then proceed to the next line.

Hope this clarifies.

---------- Post updated at 02:52 PM ---------- Previous update was at 02:20 PM ----------

Hi Shell Life,
I used the code snippet you provided and with a little bit of modifications i was able to use it. Thanks fo all the help.

Appreciate it.

4 
while IFS= read -r line; do
    case $i in
        \#*) continue;;
    esac
    printf '%s\n' "$i"
done

Of course, you'll need to feed the while loop with a pipe or a redirect or its inherited stdin.

Regards,
Alister

---------- Post updated at 05:32 PM ---------- Previous update was at 05:26 PM ----------

Don't blindly follow any mantras. In certain situations (complex error handling, for example), a well-utilized goto can significantly simplify code, and simpler code is easier to read, maintain, less buggy and perhaps faster.

Regards,
Alister

5

An interesting discussion with Linus Torvalds about the pros and cons of goto statements:

Linux: Using goto In Kernel Code | KernelTrap

1 Like