[Chapter 5] 5.5 Command History csh shell

5.5 Command History csh shell

Previously executed commands are stored in a history list. The C shell lets you access this list so you can verify commands, repeat them, or execute modified versions of them. The history built-in command displays the history list; the predefined variables histchars , history , and savehist also affect the history mechanism. Accessing the history list involves three things:

Making command substitutions (using ! and ^ ).
Making argument substitutions (specific words within a command).
Using modifiers to extract or replace parts of a command or word.

5.5.1 Command Substitution

!	Begin a history substitution.
!!	Previous command.
!`N`	Command number `N` in history list.
!-`N`	`N` th command back from current command.
!`string`	Most recent command that starts with `string` .
!?`string` ?	Most recent command that contains `string` .
!?`string` ?%	Most recent command argument that contains `string` .
!$	Last argument of previous command.
!!`string`	Previous command, then append `string` .
!`N string`	Command `N` , then append `string` .
!{`s1` }`s2`	Most recent command starting with string `s1` , then append string `s2` .
^`old` ^`new` ^	Quick substitution; change string `old` to `new` in previous command; execute modified command.

5.5.2 Command Substitution Examples

The following command is assumed:

%3 vi cprogs/01.c ch002 ch03

Event	Command	Command
Number	Typed	Executed
4	^00^0	vi cprogs/01.c ch02 ch03
5	nroff !*	nroff cprogs/01.c ch02 ch03
6	nroff !$	nroff ch03
7	!vi	vi cprogs/01.c ch02 ch03
8	!6	nroff ch03

Event	Command	Command
Number	Typed	Executed
9	!?01	vi cprogs/01.c ch02 ch03
10	!{nr}.new	nroff ch03.new
11	!!\|lp	nroff ch03.new \| lp
12	more !?pr?%	more cprogs/01.c

5.5.3 Word Substitution

Colons may precede any word specifier. After an event number, colons are optional unless shown below:

:0	Command name.
:`n`	Argument number `n` .
^	First argument.
$	Last argument.
:`n` -`m`	Arguments `n` through `m` .
-`m`	Words 0 through `m` ; same as :0-`m` .
:`n` -	Arguments `n` through next-to-last.
:`n` *	Arguments `n` through last; same as `n` -$.
*	All arguments; same as ^-$ or 1-$.
#	Current command line up to this point; fairly useless.

5.5.4 Word Substitution Examples

The following command is assumed:

%13 cat ch01 ch02 ch03 biblio back

Event	Command	Command
Number	Typed	Executed
14	ls !13^	ls ch01
15	sort !13:*	sort ch01 ch02 ch03 biblio back
16	lp !cat:3*	more ch03 biblio back
17	!cat:0-3	cat ch01 ch02 ch03
18	vi !-5:4	vi biblio

5.5.5 History Modifiers

Command and word substitutions can be modified by one or more of the following:

5.5.5.1 Printing, Substitution, and Quoting

:p	Display command but don't execute.
:s/`old` /`new`	Substitute string `new` for `old` , first instance only.
:gs/`old` /`new`	Substitute string `new` for `old` , all instances.
:&	Repeat previous substitution ( :s or ^ command), first instance only.
:g&	Repeat previous substitution, all instances.
:q	Quote a wordlist.
:x	Quote separate words.

5.5.5.2 Truncation

:r	Extract the first available pathname root.
:gr	Extract all pathname roots.
:e	Extract the first available pathname extension.
:ge	Extract all pathname extensions.
:h	Extract the first available pathname header.
:gh	Extract all pathname headers.
:t	Extract the first available pathname tail.
:gt	Extract all pathname tails.

5.5.6 History Modifier Examples

From above, command number 17 is:

%17 cat ch01 ch02 ch03

Event	Command	Command
Number	Typed	Executed
19	!17:s/ch/CH/	cat CH01 ch02 ch03
20	!:g&	cat CH01 CH02 CH03
21	!more:p	more cprogs/01.c (displayed only)
22	cd !$:h	cd cprogs
23	vi !mo:$:t	vi 01.c
24	grep stdio !$	grep stdio 01.c
25	^stdio^include stdio^:q	grep "include stdio" 01.c
26	nroff !21:t:p	nroff 01.c (is that want I wanted?)
27	!!	nroff 01.c (execute it)