Korn Shell Krankiness

5 Responses to Korn Shell Krankiness

1. bturnip says:

   August 25, 2005 at 3:09 pm

   I went home to play with my Fedora Core 3 system with the bash shell. I was relieved to find that the variable expansion as listed in the main article does work in the Bash shell, i.e.:
   
foo=teststring
bar=${foo:1:5}
echo $bar

   This will indeed give me what I expect, printing $bar gives me “estst”.

   For my script at work, I approached the problem from a different angle. Instead of screwing around with variable expansion or Korn shell built-ins, I decided to use the cut command. Back to basics.
   Dead simple, even better than using Perl to get my cherished familiar substr() function.

   
cut -b3-18 my_input.txt > my_output.txt


   Man, that is simple!

   Here’s a Perl script that does the same thing with a whole lot more code:

   #!/usr/bin/perl -w
   
   # open files
   open(INPUT,"my_input.txt")   || die "cannot open input file";
   open(OUTPUT, "> my_output.txt") || die "cannot open output file";
   
   while()
     {
      # extract the desired substring
      # add a newline to the end
      $snip=substr($_,3,18) . "n";
      # pump the new string into the output file
      print OUTPUT $snip; 
     }
   close(INPUT);
   close(OUTPUT);
   
   
   exit;
   

   Reply
2. Jon Kreisler says:

   August 30, 2007 at 2:21 pm

   The ksh93 version of ksh DOES support the syntax:

   foo=teststring
   bar=${foo:0:5}
   echo $bar

   see http://www.kornshell.com/

   Reply
3. Vij says:

   October 23, 2007 at 2:19 pm

   in Korn shell substring function : error :

   The specified substitution is not valid for this command

   shows up again and again!!! Bash is much better than ksh.

   Reply
4. Vij says:

   October 23, 2007 at 2:32 pm

   when trying to extract substring using awk, it throws up error : can not process more than 3000 bytes.

   You can rely upon sed or `cut -c 1-80` commands to extract substring when bash is not available.

   Reply
5. Vij says:

   October 23, 2007 at 2:33 pm

   awk: Input line : execut cannot be longer than 3,000 bytes.

   Reply