Redirecting Command Events - Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual

second one searches for the command in each directory given by the PATH environment
variable.

5.3 Redirecting Command Events

Each command can use three channels, either for input or output:
• Standard Output
prints something, it uses the standard output channel.
• Standard Input
uses this channel.
• Standard Error
To redirect these channels, there are the following possibilities:
Command > File
Saves the output of the command into a file, an existing file will be deleted. For
example, the ls command writes its output into the file listing.txt:
ls > listing.txt
Command >> File
Appends the output of the command to a file. For example, the ls command ap-
pends its output to the file listing.txt:
ls >> listing.txt
Command < File
Reads the file as input for the given command. For example, the read command
reads in the content of the file into a variable:
read a < foo
Command1 | Command2
Redirects the output of the left command as input for the right command.
Every channel has a file descriptor: 0 (zero) for standard input, 1 for standard output
and 2 for standard error. It is allowed to insert this file descriptor before a < or > char-
46 Administration Guide
This is the default output channel. Whenever a command
If a command needs input from users or other commands, it
Commands use this channel for error reporting.