 |  |
3.4. Common Features
The following table displays features that are common to the Bourne, Korn, and C shells. Note that the Korn shell is an enhanced version of the Bourne shell; therefore, the Korn shell includes all features of the Bourne shell, plus some others. The commands bg, fg, jobs, stop, and suspend are available only on systems that support job control. (Essentially all modern Unix systems do.)
| Symbol/Command | Meaning/Action |
|---|---|
| > | Redirect output. |
| >> | Append to file. |
| < | Redirect input. |
| << | “Here” document (redirect input). |
| | | Pipe output. |
| |& | Start a coprocess. Korn shell only. |
| & | Run process in background. |
| ; | Separate commands on same line. |
| * | Match any character(s) in filename. |
| ? | Match single character in filename. |
| [ ] | Match any characters enclosed. |
| ( ) | Execute in subshell. |
| ‘ ‘ | Substitute output of enclosed command. |
| " " | Partial quote (allows variable and command expansion). |
| ' ' | Full quote (no expansion). |
| \ | Quote following character. |
| $var | Use value for variable. |
| $$ | Process ID. |
| $0 | Command name. |
| $n | nth argument (0  n 9). |
| $* | All arguments as simple words. |
| # | Begin comment. |
| bg | Background execution. |
| break | Break from loop statements. |
| cd | Change directory. |
| continue | Resume a program loop. |
| echo | Display output. |
| eval | Evaluate arguments. |
| exec | Execute a new shell. |
| fg | Foreground execution. |
| jobs | Show active jobs. |
| kill | Terminate running jobs. |
| shift | Shift positional parameters. |
| stop | Suspend a background job. |
| suspend | Suspend a foreground job (such as a shell created by su). |
| time | Time a command. |
| umask | Set default file permissions for new files. |
| unset | Erase variable or function definitions. |
| wait | Wait for a background job to finish. |
|  | |
| 3.3. Shell Flavors |  | 3.5. Differing Features |
Copyright © 2003 O'Reilly & Associates. All rights reserved.