B.3. Built-In Commands and Reserved Words

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Table B-4 shows a summary of all built-in commands and reserved words. The letters in the Type column of the table have the following meanings: R = reserved word, blank = Builtin.

Table B-4. Commands and reserved words

Command

Chapter

Type

Summary

!

5

R

Logical NOT of a command exit status.

:

7

 

Do nothing (just do expansions of any arguments).

.

4

 

Read file and execute its contents in current shell.

alias

3

 

Set up shorthand for command or command line.

bg

8

 

Put job in background.

bind

2

 

Bind a key sequence to a readline function or macro.

break

5

 

Exit from surrounding for, select, while, or until loop.

builtin

5

 

Execute the specified shell built-in.

case

5

R

Reserved word. Multi-way conditional construct.

cd

1

 

Change working directory.

command

7

 

Run a command bypassing shell function lookup.

compgen

D

 

Generate possible completion matches.

complete

D

 

Specify how completion should be performed.

continue

  

Skip to next iteration of for, select, while, or until loop.

declare

6

 

Declare variables and give them attributes.

dirs

6

 

Display the list of currently remembered directories.

disown

8

 

Remove a job from the job table.

do

5

R

Part of a for, select, while, or until looping construct.

done

5

R

Part of a for, select, while, or until looping construct.

echo

4

 

Expand and print any arguments.

elif

5

R

Part of an if construct.

else

5

R

Part of an if construct.

enable

7

 

Enable and disable built-in shell commands.

esac

5

R

Part of a case construct.

eval

7

 

Run the given arguments through command-line processing.

exec

9

 

Replace the shell with the given program.

exit

5

 

Exit from the shell.

export

3

 

Create environment variables.

fc

2

 

Fix command (edit history file).

fg

8

 

Put background job in foreground.

fi

5

R

Part of an if construct.

for

5

R

Looping construct.

function

4

R

Define a function.

getopts

6

 

Process command-line options.

hash

3

 

Full pathnames are determined and remembered.

help

1

 

Display helpful information on built-in commands.

history

1

 

Display command history.

if

5

R

Conditional construct.

in

5

R

Part of a case construct.

jobs

1

 

List any background jobs.

kill

8

 

Send a signal to a process.

let

6

 

Arithmetic variable assignment.

local

4

 

Create a local variable.

logout

1

 

Exits a login shell.

popd

4

 

Removes a directory from the directory stack.

pushd

4

 

Adds a directory to the directory stack.

pwd

1

 

Print the working directory.

read

7

 

Read a line from standard input.

readonly

6

 

Make variables read-only (unassignable).

return

5

 

Return from the surrounding function or script.

select

5

R

Menu-generation construct.

set

3

 

Set options.

shift

6

 

Shift command-line arguments.

suspend

  

Suspend execution of a shell.

test

5

 

Evaluates a conditional expression.

then

5

R

Part of an if construct.

time

 

R

Run command pipeline and print execution times. The format of the output can be controlled with TIMEFORMAT.

times

  

Print the accumulated user and system times for processes run from the shell.

trap

8

 

Set up a signal-catching routine.

type

3

 

Identify the source of a command.

typeset

6

 

Declare variables and give them attributes. Same as declare.

ulimit

10

 

Set/show process resource limits.

umask

10

 

Set/show file permission mask.

unalias

3

 

Remove alias definitions.

unset

3

 

Remove definitions of variables or functions.

until

5

R

Looping construct.

wait

8

 

Wait for background job(s) to finish.

while

5

R

Looping construct.


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    Learning the bash Shell
    Learning the bash Shell: Unix Shell Programming (In a Nutshell (OReilly))
    ISBN: 0596009658
    EAN: 2147483647
    Year: 2005
    Pages: 139

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