| : | Do-nothing command; returns exit status 0. |
| . file | The dot command reads and executes a command from file. |
| break | See "The break Command" on page 699. |
| continue | See "The continue Command" on page 700. |
| cd | Changes directory. |
| echo [ args ] | Displays arguments. |
| eval command | Shell scans the command line twice before execution. |
| exec command | Runs command in place of this shell. |
| exit [ n ] | Exit the shell with status n . |
| export [ var ] | Makes var known to subshells. |
| fc “e [ editor ] [ lnr ] first last | Used to edit commands in the history list. If no editor is specified, the value of FCEDIT is used; if FCEDIT is not set, /bin/ed is used. Usually history is aliased to fc “l . E XAMPLES |
| fc “l | Lists the last 16 commands on the history list. |
| fc “e emacs grep | Reads the last grep command into the emacs editor. |
| fc 25 30 | Reads commands 25 through 30 into the editor specified in FCEDIT , by default the ed editor. |
| fc “e “ | Re-executes the last command. |
| fc “e “ Tom=Joe 28 | Replaces Tom with Joe in history command 28 . |
| fg | Brings the last background job to the foreground. |
| fg %n | Brings job number n to the foreground. Type jobs to find the correct job number. |
| jobs [ “l] | Lists the active jobs by number and with the “l option by PID number. E XAMPLES $ jobs [3] + Running sleep 50& [1] Stopped vi [2] Running sleep%
|
| kill [ “signal process ] | Sends the signal to the PID number or job number of process. See /usr/include/sys/signal.h for a list of signals. S IGNALS |
| SIGHUP1 /* hangup (disconnect) */ |
| SIGINT 2 /* interrupt */ |
| SIGQUIT 3 /* quit */ |
| SIGILL 4 /* illegal instruction (not reset when caught) */ |
| SIGTRAP 5 /* trace trap (not reset when caught) */ |
| SIGIOT 6 /* IOT instruction */ |
| SIGABRT 6 /* used by abort, replace SIGIOT in the future */ |
| SIGEMT 7 /* EMT instruction */ |
| SIGFPE 8 /* floating-point exception */ |
| SIGKILL 9 /* kill (cannot be caught or ignored) */ |
| SIGBUS 10 /* bus error */ |
| SIGSEGV 11 /* segmentation violation */ |
| SIGSYS 12 /* bad argument to system call */ |
| SIGPIPE 13 /* write on a pipe with no one to read it */ |
| SIGALRM 14 /* alarm clock */ |
| SIGTERM 15 /* software termination signal from kill */ |
| SIGURG 16 /* urgent condition on I/O channel */ |
| SIGSTOP 17 /* sendable stop signal not from tty */ |
| SIGTSTP 18 /* stop signal from tty */ |
| SIGCONT 19 /* continue a stopped process */ |
| | EXAMPLES (To use the kill command and a signal name , strip off the SIG prefix and precede the signal name with a dash.) kill INT %3 kill HUP 1256 kill 9 %3 kill %1
|
| getopts | Used in shell scripts to parse command line and check for legal options. |
| hash | Lists all tracked aliases. |
| login [ username ] | |
| newgrp [ arg ] | Changes your real group ID to the group ID. |
| print “[nrRsup] | Replacement for echo . See print . |
| pwd | Print present working directory. |
| read [ var ] | Read line from standard input into variable var . |
| readonly [ var ] | Make variable var readonly . Cannot be reset. |
| return [ n ] | Exit value given to a function. |
| set [ “aefhknoptuvx “ [ “o option] [ “A arrayname] [ arg ] ] | Examples |
| set | Lists all variables and their values. |
| set + | Lists all variables without their values. |
| set “o | Lists all option settings. |
| set a b c | Resets positional parameters $1 , $2 , $3 . |
| set “s | Sorts $1 , $2 , and $3 alphabetically . |
| set “o vi | Sets the vi option. |
| set “xv | Turns on the xtrace and verbose options for debugging. |
| set “ “ | Unsets all positional parameters. |
| set “ “ "$x" | Sets $1 to the value of x , even if x is “x . |
| set == $x | Does pathname expansion on each item in x and then sets the positional parameters to each item. |
| set “A name tom dick harry name[0] is set to tom; name[1] is set to dick ;
name[2] is set to harry .
set +A name joe name[0] is reset to joe , the rest of the array is left
alone; name[1] is dick ; name[2] is harry . |
| (To set options, use the “o flag; to unset options, use the +o flag.) set “o ignoreeof |
| Options: |
| allexport | After setting this, exports any variable defined or changed. |
| bgnice | Runs background jobs with a lesser priority; used instead of nice . |
| emacs | Sets the emacs built-in editor. |
| errexit | The shell exits when a command returns a nonzero exit status. |
| gmacs | Sets the built-in gmacs editor. |
| ignoreeof | Ignores the EOF (Ctrl-D) key from terminating the shell. Must use exit to exit. |
| keyword | Adds keyword arguments occurring anywhere on the command line to the environment of the shell. |
| markdirs | Puts a trailing backslash on all directory names resulting from filename expansion. |
| monitor | Sets job control. |
| noclobber | Prevents overwriting files using the redirection operator, > . Use > to force overwrite. |
| noexec | Same as ksh “n ; reads commands but does not execute them. Used to check for syntax errors in shell scripts. |
| noglob | Disables pathname expansion with ksh wildcard metacharacters. |
| nolog | Function definitions will not be stored in the history file. |
| nounset | Displays an error if a variable has not been set. |
| privileged | Turns on privileged mode for setuid programs. |
| trackall | Ksh causes each command to become a tracked alias; automatically turned on for interactive shells . |
| verbose | Echos each line of input to standard error; useful in debugging. |
| vi | Sets the vi built-in editor. |
| viraw | Specifies vi character at a time input. |
| xtrace | Expands each command and displays it in the PS4 prompt, with variables expanded. |
| shift [ n ] | Shifts positional parameters to the left n times. |
| times | Prints accumulated user and system times for processes run from this shell. |
| trap [ arg ] [ n ] | When shell receives signal n (0, 1, 2, or 15), arg is executed. |
| type [ command ] | Prints the type of command; for example, pwd is a built-in shell. In ksh , an alias for whence “v . |
| typeset [ options ] [ var ] | Sets attributes and values for shell variables and functions. |
| ulimit [ options size ] | Sets maximum limits on processes. E XAMPLES |
| ulimit “a | Display all limits: Time (seconds) unlimited. File (blocks) unlimited. Data (kbytes) 524280. Stack (kbytes) 8192. Memory (kbytes) unlimited. Core dump (blocks) unlimited. |
| | Other Options: |
| | “c size | Limits core dumps to size blocks. |
| | “d size | Limits the data size (of executables) to size blocks. |
| | “f size | Limits the size of files to size blocks (default). |
| | “m size | Limits the size of physical memory to size K bytes. |
| | “s size | Limits the size of the stack area to size K bytes. |
| | “t secs | Limits process execution time to secs seconds. |
| umask [ mask ] | Without argument, prints out file creation mask for permissions. |
| umask [ octal digits ] | User file creation mode mask for owner, group, and others. |
| unset [ name ] | Unsets value of variable or function. |
| wait [ pid#n ] | Waits for background process with PID number n and report termination status. |
| whence [ command ] | Prints information about the command, like ucb whereis . E XAMPLES |
| | whence “v happy | happy is a function |
| | whence “v addon | addon is an undefined function |
| | whence “v ls | ls is a tracked alias for /bin/ls |
| | whence ls | /bin/ls |
