The ! bash command. How do I use it?

funkynesh · 10-12-2005, 04:44 PM

I was wondering what is the purpose of the ! command in bash? How do I use it?

Thank you

jtshaw · 10-12-2005, 05:11 PM

If you type !<command> it repeats the last time you used said command (with the same arguements you used before).

So, for instance, if I type ps a followed by a !ps I will get the ps a output twice. This is useful if you want to re-issue a command you've used recently but don't want to have to type out a million arguements again.

Example:

Code:

johnshaw@Quaqmire-OSX ~ $ ps a
  PID  TT  STAT      TIME COMMAND
 9664  p1  Ss     0:00.02 login -pf johnshaw
 9665  p1  S      0:00.19 -bash
 9935  p1  R+     0:00.01 ps a
 9861  p2  Ss     0:00.03 login -pf johnshaw
 9862  p2  S      0:00.02 -bash
 9863  p2  S+     0:00.22 man pthread_join
 9864  p2  S+     0:00.01 sh -c (cd /usr/share/man && /usr/bin/tbl /usr/share/man/man3/pthread_join.3 | /u
 9865  p2  S+     0:00.01 sh -c (cd /usr/share/man && /usr/bin/tbl /usr/share/man/man3/pthread_join.3 | /u
 9868  p2  S+     0:00.01 /usr/bin/less -is
johnshaw@Quaqmire-OSX ~ $ !ps 
ps a
  PID  TT  STAT      TIME COMMAND
 9664  p1  Ss     0:00.02 login -pf johnshaw
 9665  p1  S      0:00.19 -bash
 9936  p1  R+     0:00.01 ps a
 9861  p2  Ss     0:00.03 login -pf johnshaw
 9862  p2  S      0:00.02 -bash
 9863  p2  S+     0:00.22 man pthread_join
 9864  p2  S+     0:00.01 sh -c (cd /usr/share/man && /usr/bin/tbl /usr/share/man/man3/pthread_join.3 | /u
 9865  p2  S+     0:00.01 sh -c (cd /usr/share/man && /usr/bin/tbl /usr/share/man/man3/pthread_join.3 | /u
 9868  p2  S+     0:00.01 /usr/bin/less -is
johnshaw@Quaqmire-OSX ~ $

funkynesh · 10-12-2005, 08:36 PM

Thanks!

But I saw combination of command like this one: !?<word>.

Why the ?, I understand that it tells bash to launch the last command that had <word> in it. A more in-depth explanation of the different combination you can use would be appreciate or a link to a document explaining it.