Bash – Does one alias affect another alias

aliasbash

I don't have many aliases set up in my .bash_aliases file just yet. Only recently have I discovered how useful they can be.

I can see myself getting quite hooked on aliases so before the file gets too unwieldy I'd like to clarify something by asking a very simple question. Does one alias affect another, or does the alias always revert back to the original command?

An example may make this more clear:

I have ls aliased to ls -lF. Let's say I'd like to also alias d to ls -l | grep -E "^d": does d now use ls -lF in place of ls? If so, is it a matter of order in the .bash_aliases configuration file?

man alias didn't enlighten me.

Best Answer

From Aliases (section 6.6 of the Bash Manual):

The first word of each simple command, if unquoted, is checked to see if it has an alias. If so, that word is replaced by the text of the alias.

This happens when you use the alias, not when you define it. Here's an example:

$ alias a1='a2 hello'
$ alias a2='echo'
$ a1
hello
$ unalias a2
$ a1
bash: a2: command not found

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Bash – Writing bash function as one-line alias

As @AndreasWiese comments, you can't do this with an alias. Aliases tack on arguments space-separated, so you can't join them (in a simple way) to the aliased command.

A comment on your function: Why are you using $@? You should use $1 instead. If you call your function with multiple arguments (p a b c), you'll probably get ~~an error (b: command not found)~~ an unknown directory.

Bash – Forward aliases to child process

You shouldn't define aliases in /etc/zprofile or ~/.zprofile. These files is only loaded in login shells (“shells” meaning zsh of course). The proper place to define aliases is in /etc/zshrc or ~/.zshrc, which is read by all interactive shells.

To run zsh without loading /etc/zprofile, just run zsh with no option. The option -f tells zsh not to read configuration files at all, but since you want to read your alias definitions, that's not the right option. Since /etc/zprofile is only read by a login shell, just don't pass the -l option (and don't set a zeroth argument that begins with a dash).

Zsh has no option or environment variable to read one extra file on startup. If you want to prepare for that, you can add eval $ZSH_EXTRA_STARTUP_CODE to your .zshrc.

You can set the ZDOTDIR environment variable to make it read all of its user configuration files from a different directory, e.g. ZDOTDIR=/tmp/foo zsh reads /etc/zshenv, /tmp/foo/.zshenv, /etc/zshrc and /tmp/foo/zshrc. So to export aliases from the current instance to a child instance, you can run something like

tmp=$(mktemp -d)
alias -L >$tmp/.zshenv
echo ". ~/.zshenv; unset ZDOTDIR; rm -r ${(q)tmp}" >>$tmp/.zshenv
zsh

Best Answer

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Bash – Writing bash function as one-line alias

Bash – Forward aliases to child process

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