The following features are standard in every shell. Note that the stop, suspend, jobs, bg and fg commands are only available on systems that support job control.
Table A-1. Common Shell Features
Command | Meaning |
---|---|
> | Redirect output |
>> | Append to file |
< | Redirect input |
<< | "Here" document (redirect input) |
| | Pipe output |
& | 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 (n from 0 to 9) |
$* | All arguments as a simple word |
# | Begin comment |
bg | Background execution |
break | Break from loop statements |
cd | Change directories |
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 |
newgrp | Change to a new group |
shift | Shift positional parameters |
stop | Suspend a background job |
suspend | Suspend a foreground job |
time | Time a command |
umask | Set or list file permissions |
unset | Erase variable or function definitions |
wait | Wait for a background job to finish |