c shell redirection.

http://www.mathinfo.u-picardie.fr/asch/f/MeCS/courseware/users/help/general/unix/redirection.html

http://hi.baidu.com/sanshan/blog/item/98e4c3ce3313690593457e69.html


http://www.linuxdevcenter.com/pub/a/linux/lpt/13_01.html (this is the best link I have seen)

Table 1: Common Standard I/O Redirections

Function	csh	sh
Send stdout to file	prog > file	prog > file
Send stderr to file		prog 2> file
Send stdout and stderr to file	prog >& file	prog > file 2>&1
Take stdin from file	prog < file	prog < file
Send stdout to end of file	prog >> file	prog >> file
Send stderr to end of file		prog 2>> file
Send stdout and stderr to end of file	prog >>& file	prog >> file 2>&1
Read stdin from keyboard until c	prog <<c	prog <<c
Pipe stdout to prog2	prog | prog2	prog | prog2
Pipe stdout and stderr to prog2	prog |& prog2	prog 2>&1 | prog2

The C shell doesn't give you an easy way to redirect standard output without redirecting standard error. A simple trick will help you do this. To put standard output and standard error in different files, give a command like:

% ( prog > output ) >& errors