Alias does not "override" PATH entries?
The which
command returns only executables: it knows nothing about aliases, since it is an external program, and there is no mechanism for passing alias information to a child process.
If you enter the command type -a cp
you will see all possible interpretations, in order of preference. This includes any alias, since type
is a bash
internal command.
It is important to realise that an alias will not be interpreted by a sub-process, such as a script or an interactive editor which has an option to run system commands.
If you make cp
a function, then your version will run in scripts, though not from other programs:
cp() { /usr/local/bin/gcp "$@"; }
If you want your cp
to work everywhere, add $HOME/bin
at the head of your PATH
list and point $HOME/bin/cp
to point to it:
ln -s /usr/local/bin/gcp $HOME/bin/cp
This makes a symbolic link, though you can make it a slightly more efficient hard link (omit -s
), but this will normally need root permissions (sudo ln ...
). Creating a function and adding to the PATH
variable will be done in one of the bash
start-up scripts, with user permissions.
Aliases are internal to the shell. Other programs won't know about them.
which
is not a Bash builtin (it is a builtin in some other shells, e.g. zsh). Since which
has no privileged information into Bash's aliases, which
just looks through PATH
for the given term.
type
, on the other hand is a Bash builtin, so it can report on aliases.