 |
Csh provides a list of commands that you have typed in, as
well as a rich set of designators and modifiers. The size of
the history list is controlled by the history variable. Each
entry in the history list, known as an event, is numbered
sequentially, however the start of the list does not
necessarily start at zero, since old events are removed from
the list once the number of events reach the value of the
history variable. You can specify previous events by its
absolute number, its relative number to the current event, or
a sub-string matching all or part of a previous event. You
use a ! character (also called a bang) to specify a history
event.
You recall a previous event by its number using:
-
!n
-
where n is the event number by it's relative number to the
current event;
-
!-n
-
where n is the nth previous event.
-
by a sub-string beginning an event name on the history list
-
!<string>, where string begins an
event on the list. It is not necessary to specify the whole
word (or command name), just enough to specify the one you
want. If it matches more than one event, the shell will use
the most recent event.
-
by a sub-string of an event
-
!?<string>?, where string is
appears in any part of a previous event. Again, it is not
necessary to specify an entire word, and duplicate matches
will get you the most resent event.
-
to execute the last command you can simply type:
!!
A string in the above selectors is a word, not a string of
words. When you use !command x, x becomes an
argument following the history completion of
!command.
For some examples, we first need a history list, so suppose
we have:
19 emacs ~/private/resume
20 ls docs/politics
21 more docs/politics/U.S.house.email.addresses
22 mail georgia6@hr.house.gov
23 telnet wam
-
!21
-
would repeat the command more
docs/politics/U.S.house.email.addresses
-
!m
-
would repeat the command mail
georgia6@hr.house.gov, since we only used m, it found
the first command that started with m, to specify the last
more command we would use !mo.
-
!-5
-
would recall the emacs command, since that is 5th last
command we typed.
-
!?priv?
-
would recall the emacs command, since that is the last
command that contained the word priv (i.e. private).
|
