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| Chapter 7 Setting Your Shell Prompt |

## 7.3 C Shell Prompt Causes Problems in vi, rsh, etc.

[Stray prompts can cause trouble for many commands that start a noninteractive shell. This problem may have been fixed in your C shell. The point Chris makes about speeding up your .cshrc still applies, though. -JP]

If you set prompt in your .cshrc file without carefully checking first whether or not prompt was already set (2.9), many versions of the C shell will cheerfully print prompts into the pipe vi uses to expand glob characters [ filename wildcards (`*`, `?`, `[]`) (1.16) and the tilde (`~`) (14.11) -JP ].

When you type `:r abc*`, vi opens a pipe to the C shell and writes the command `echo abc*` down the pipe, then reads the response. If the response contains spaces or newlines, vi gets confused. If you set your prompt to `(``n``)` in your .cshrc [i.e., if you show the history number in parentheses as the prompt-TOR ], vi tends to get:

>     (1) abc.file (2)

back from the C shell, instead of just `abc.file`.

The solution is to kludge your .cshrc (2.9) like this:

    if $?prompt
    if ($?prompt) then
        # things to do for an interactive shell, like:
        set prompt='(\!) '
    endif

This works because a noninteractive shell has no initial prompt, while an interactive shell has it set to `%` .

If you have a large .cshrc, this can speed things up quite a bit when programs run other programs with `csh` `-c` `'``command``'`, if you put all of it inside that test.

- CT in net.unix-wizards on Usenet, 22 April 1984

7.2 Basics of Setting the Prompt |  | 7.4 Faster Prompt Setting with Built-Ins