Question

Many years ago, I did “which cd” and it told me “cd: shell built-in command.”

Recently, I tried it and got:

/usr/bin/which: no cd in ([obscenely long path I will not reproduce here])

I investigated and found that someone had aliased which:

> which which 
which   alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde 
        /usr/bin/which 

Once I unaliased which, “which cd” worked again properly. My questions:

• How can I make “which” work with both aliases AND shell built-ins?

• I couldn’t find where the “which” alias is created (it’s not in
  /etc/cshrc, ~/.cshrc, etc for example). Where does this happen so I
  can defeat/edit it permanently?

EDIT: Thanks to everyone who helped. I think I’ve figured this out:

• “which” is a tcsh built-in, not the same thing as “/usr/bin/which”:

> unalias which; which which
which: shell built-in command. 

• “unalias which” pretty much does the trick. It works with builtins
  (as above) and aliases (and correctly recognizes the backslash as an
  alias escape), as below:

 
> alias foo bar; which foo 
foo:     aliased to bar 

> which \foo 
foo: Command not found. 

• The alias appears to come from /etc/profile.d/which2.csh on my
  system, which is odd because I thought profile.d was only for
  sh/bash, not csh/tcsh

Answer 1

On Redhat systems, it looks like its defined in /etc/profile.d/which.sh

To try the unaliased command I did:

 /usr/bin/which cd
/usr/bin/which: no cd in (/usr/lib64/ccache:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin)

so I’m not sure where your builtin output is coming from.