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[previous article] [next article]Do you use C-shell?
Do you use history commands?
Do you like to save keystrokes?
If you do, then you already know the time saving power of reissuing commands without retyping the whole command line; or altering a previously issued command line while only typing the changes! If you don't already use this convenient power, you might consider using C-shell. Type "chsh" to convert to the C- shell; then set up history in your .chsrc file by adding "set history=XX" where XX is the max number of commands kept in the history list (for example, "set history=22").
Once history is in place, UNIX keeps a running list of command lines you have issued this computing session. A history listing obtained by typing "history" might look like:
1 mail 2 date 3 cat myfile 4 nmt. -Tpsc -t -e -g -o1-22 myfile | lpr -Pka2 -n -hg
To re-execute the last command, type "!!" at the C-shell prompt. If the nmt command were not the immediately preceding one, you could reference it by typing "!nmt" (a unique pattern for C- shell to find) or "!4" (the number of the command in the history listing).
Sometimes, you will type a long command with a typographical error in it! Here are 2 ways to change a UNIX command in C- shell. For example, say you wanted to send a troff job to the ka2 Apple LaserWriter, and you wanted pages 1,2,3,...,11. You would use the option "-o1-11". If you made a typo and typed "- o1-22", you could abort the command with control-c before sending it and re-execute it with the corrections.
One example would be:
Original command line:
% nmt. -Tpsc -t -e -g -o1-22 myfile | lpr -Pka2 -n -h
Correction:
% ^22^11
Altered command line:
% nmt. -Tpsc -t -e -g -o1-11 myfile | lpr -Pka2 -n -hg
Another example would be:
Original command line:
% nmt. -Tpsc -t -e -g -o1-22 myfile | lpr -Pka2 -n -h
Correction:
% !!:s/22/11
Altered command line:
% nmt. -Tpsc -t -e -g -o1-11 myfile | lpr -Pka2 -n -hg
You can also make GLOBAL changes of the UNIX command, but you must be careful, since all occurrences will change! For example, if you did a global substitution of 1 for 2, you would also change the printer name (ka2 -> ka1)!!
Original command line:
% nmt. -Tpsc -t -e -g -o1-22 myfile | lpr -Pka2 -n -h
Correction:
% !!:gs/2/1
Altered command line:
% nmt. -Tpsc -t -e -g -o1-11 myfile | lpr -Pka1 -n -hg
The caret method (^) only works on the immediately preceding command. The substitution method (:s/old/new) can work on any referenced command.
If C-shell looks interesting and you want to find out more details, please attend the free UNIX seminar for instruction,
September 26, 1989 at 10:30am in CE1144
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