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| |
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
| ! | Begin a history substitution |
| !! | Previous command |
| !N | Command number N in history list |
| !-N | Nth 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 |
The following command is assumed:
3% vi cprogs/01.c ch002 ch03
| Event Number | Command Typed | Command 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 |
| 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 |
Word specifiers allow you to retrieve individual words from previous command lines. Colons may precede any word specifier. After an event number, colons are optional unless shown here.
| :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 |
The following command is assumed:
13% cat ch01 ch02 ch03 biblio back
| Event Number | Command Typed | Command Executed |
|---|---|---|
| 14 | ls !13^ | ls ch01 |
| 15 | sort !13:* | sort ch01 ch02 ch03 biblio back |
| 16 | lp !cat:3* | lp ch03 biblio back |
| 17 | !cat:0-3 | cat ch01 ch02 ch03 |
| 18 | vi !-5:4 | vi biblio |
Command and word substitutions can be modified by one or more of these:
| :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 word list. |
| :x | Quote separate words. |
| :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. |
From the table in Section 5.5.4, command number 17 is:
17% cat ch01 ch02 ch03
| Event # | Command Typed | Command 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) |
|  | |
| 5.4. Expressions |  | 5.6. Job Control |
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