How can I determine my csh version?

Question

I have some code which works for me, but when I gave it to some colleagues, it broke. They're using tcsh whereas, as far as I can figure, I'm using csh.

I've tried:

csh -v
csh --version
csh -V
csh --help
csh -h

with no success (they all just take me straight to the interpreter prompt). I've also grepped the man page for the string "version", but I didn't come up with anything useful there either. Is there a way to determine the version of csh that I have installed?

-- Edit --

Following the symbolic links from /bin/csh, they seem to terminate at /bin/bsd-csh which seems to imply that I'm using some BSD flavor csh shell if that helps anyone. Also, I'm using ubuntu linux.

Answer 1

In comments, you've indicated that you're on Ubuntu, and that /bin/csh is a symlink to /etc/alternatives/csh, which is a symlink to /bin/csh.

The csh shell originated on BSD Unix, so it's not surprising that csh is an indirect symlink to /bin/bsd-csh. It goes back to 1978 or so, before it became common for Unix program to report their own version numbers.

Since you're on Ubuntu, this:

dpkg -l csh

should tell you what version you have -- though the version number of the Debian/Ubuntu package isn't likely to be more useful than the information you already have. And the relationship between the package version number and the version of the shell isn't entirely clear.

I'm assuming that's the right package name. If not, try dpkg -S /bin/bsd-csh.

You can tell whether you're running tcsh or not, like this:

if ($?tcsh) then
    echo This is tcsh
else
    echo This is csh, not tcsh
endif

tcsh is supposed to be backward compatible with csh, with some extra features, mostly for interactive use. A script written for tcsh could easily fail under csh if it uses tcsh-specific features, but I'd expect tcsh to be able to handle a csh script. As the tcsh(1) man page says:

tcsh is an enhanced but completely compatible version of the Berkeley UNIX C shell, csh(1).

I understand you probably can't post the entire failing script, but can you post a small representative example that works for you and fails for your colleagues?

One solution might be to ask you colleagues to install vanilla csh on their systems; they can still use /bin/tcsh as their interactive shell if they like, but #!/bin/csh would then cause the script to be executed by the old csh, not tcsh.

Finally, I can't answer a question about [t]csh scripting without adding a link to this.

Addendum: I have access to a Solaris system with a /bin/csh that isn't tcsh; I can run some simple tests there if you like. One data point: both /bin/tcsh and /bin/csh accept : as a null command, but with /bin/csh it doesn't accept arguments:

% :
% arg
:: Too many arguments

Answer 2

csh --version would work only if csh is actually a symlink to... /bin/tcsh(!)

Otherwise, a csh session doesn't seem to set any version, except in this MKSToolkit, where that csh is supposed to set a variable $csh_version.

Pre-defined Variables

The following variables have special meaning to the C Shell.
Of these, argv, csh_version, cwd, home, path, prompt, ROOTDIR, shell, status, COMSPEC, and TMPDIR are always set by the shell.
Except for cwd and status, this setting occurs only at initialization; these variables are then not modified unless done explicitly by the user.

See this dotfile for instance:

shell_is_csh  () { return [ -n "$csh_version"  ]; }

---

/bin/csh links to /etc/alternatives/csh which links to /bin/bsd-csh.
Apparently it's bsd-csh

... then bsd-csh doesn't seem to support any kind of version feature.