B.7 I/O Redirection

Table 2.8 shows a complete list of I/O redirectors. (This table is also included earlier as Table 7.1.) Note that there are two formats for specifying standard output and error redirection: &>file and >&file. The second of these, and the one used throughout this book, is the preferred way.

Table B.8. I/O Redirectors
Redirector	Function
cmd1 | cmd2	Pipe; take standard output of cmd1 as standard input to cmd2
> file	Direct standard output to file
< file	Take standard input from file
>> file	Direct standard output to file; append to file if it already exists
>| file	Force standard output to file even if noclobber is set
n>| file	Force output to file from file descriptor n
	even if noclobber set
<> file	Use file as both standard input and standard output
n<> file	Use file as both input and output for file descriptor n
<< label	Here-document
n> file	Direct file descriptor n to file
n< file	Take file descriptor n from file
>> file	Direct file descriptor n to file; append to file if it already exists
n>&	Duplicate standard output to file descriptor n
n<&	Duplicate standard input from file descriptor n
n>&m	File descriptor n is made to be a copy of the output file descriptor
n<&m	File descriptor n is made to be a copy of the input file descriptor
&>file	Directs standard output and standard error to file
<&-	Close the standard input
>&-	Close the standard output
n>&-	Close the output from file descriptor n
n<&-	Close the input from file descriptor n