I am Oracle DBA, I am trying to learn unix korn shell. I can use/know most of the commnand in unix so I can get around the OS; however, I would like to learn more about korn shell.

1. does anyone know the good book that I can use to start?
2. time to time, I saw this command in a lot of shell scripts but not sure what exactly it's doing

for example:
@ls -l $PASSWORD_FILE > /dev/null 2 >&1

basically, I understand it's doing a list for the password file then write to /dev/null, but what is 2 > &1 mean?

thx

Hi,

That depends a bit on the KSH dialect you are using, but 'Learning the Korn Shell' (Bill Rosenblatt - O'Reilly) should get you going. It is based on ksh88, but I never had any trouble with pdksh (most unix distro's carry this one).

I also have the 'Hands-On KornShell93 Programmnig' book (Barry Rosenberg - Addison Wesley). Great book, nice examples and all is clearly explained. The downside is that ksh93 isn't the same as ksh88/pdksh........

2 > &1 -> all that is written to file descriptor 2 (stderr) is redirected to file descriptor 1 (stdout).

.... > /dev/null could also be written as .... 1> /dev/null
Both forms are correct although the second example is (hopefully) easier to understand.

So this .... > /dev/null 2 >&1 will redirect both stdout (the > or 1>) and stderr (2>) to /dev/null, by means of redirecting stderr to file descriptor 1 (the &1 part).

Hope this clears things up a bit.

Hi,

Welcome to LQ!

I would suggest that you provide a title that is a bit more descriptive to your question. I would suggest that you view the next two Links;

All the ksh info you could ever want:

http://kornshell.com/