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How the Shell Interprets What You Type
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8.3 Introduction to tcsh

Article 8.2 introduces bash and talks about shells that came before it. A lot of shell users prefer tcsh . It's like the C shell, but tcsh has added plenty of useful features and also fixed some notorious C shell bugs ( 47.2 ) . In fact, tcsh is so much like csh (except for those ugly bugs) that when we say "the C shell" or csh in this book, we're also talking about tcsh .

In general, tcsh has a lot of the same features as bash . So I won't repeat the list from article 8.2 . Instead, here are a few differences (from the point of view of a casual tcsh user like me, that is).

  • My favorite tcsh feature confirms a command like the one below. I meant to type rm *.c :

    rm * .c
    Do you really want to delete all files? [n/y] 

    In my opinion, tcsh keeps a better watch over the command line than bash does.

  • My dyslexic fingers also like the automatic command name correction. In the next example, I type srot . Instead of saying Command not found , tcsh asks if I meant sort :

    who | srot +3n +4
    CORRECT>who | sort +3n +4 (y|n|e|a)? 
    kim            pts/0        Jul 27 14:40  (rock.ny.ora.com)
    jpeek          pts/1        Jul 28 08:09  (jpeek.com)

  • Like csh , tcsh has arrays ( 47.5 ) . I find these really useful, both interactively and in shell programs. ( bash won't have them until version 2.0.)

  • On the downside, the shell variables - including prompts, and their setting - seem less flexible in tcsh . For example, resetting the prompt (except nice built-ins like %c2 , which gives the last two parts of the current directory path) requires setting aliases.

If you've used csh before, and you type more than a few commands a day on UNIX, check out tcsh . It's on the CD-ROM.

- JP

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