Table B-9 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-9. 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 |
| n>&word | If n is not specified, the standard output (file descriptor 1) is used; if the digits in word do not specify a file descriptor open for output, a redirection error occurs; as a special case, if n is omitted, and word does not expand to one or more digits, the standard output and standard error are redirected as described previously |
| n<&word | If word expands to one or more digits, the file descriptor denoted by n is made to be a copy of that file descriptor; if the digits in word do not specify a file descriptor open for input, a redirection error occurs; if word evaluates to -, file descriptor n is closed; if n is not specified, the standard input (file descriptor 0) is used |
| n>&digit- | Moves the file descriptor digit to file descriptor n, or the standard output (file descriptor 1) if n is not specified |
| n<&digit- | Moves the file descriptor digit to file descriptor n, or the standard input (file descriptor 0) if n is not specified; digit is closed after being duplicated to n |
