help with using alias in bash shell

Question

i want to have an alias "t" to enter a folder and list the content there.

i tried with:

alias t="cd $1; ls -la"

but it just listed the folder i typed but did not enter it. i wonder why?

cause when i use this one:

alias b="cd ..; ls"

it went back to the parent and listed the content.

so i want the "t" do enter the folder i type in too.

someone knows how to do this right?

jimyi · Answer 1 · 2010-04-04T00:23:13.933

4

You can't pass arguments into bash aliases. You'll need to create a shell function like so:

function t { cd "$1" && ls -la; }

Edit: whoops, forgot the function and edited per Juliano's suggestion.

edited Apr 04 '10 at 00:23

answered Apr 03 '10 at 17:01

jimyi

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`function t` or `t()` at the beginning. – Ignacio Vazquez-Abrams Apr 03 '10 at 17:05
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I suggest replacing `;` with `&&`. It doesn't make a lot of sense to run ls if the user mistypes the directory name. – Juliano Apr 03 '10 at 17:35

score 2 · Accepted Answer · answered Apr 03 '10 at 17:02

2

I don't think you can use aliases that way. You can, however, declare a function:

function t {
    cd "$1"
    ls -la
}

answered Apr 03 '10 at 17:02

Thomas

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score 1 · Answer 3 · edited May 23 '17 at 10:27

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cd is tricky in bash. The command you issued ran in a separate process than your bash shell, and that process terminated when it was done. See Why doesn't "cd" work in a bash shell script?

edited May 23 '17 at 10:27

Community

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answered Apr 03 '10 at 17:14

Michael Munsey

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Nope, that's not the reason in this case. – Dennis Williamson Apr 03 '10 at 17:30
The `cd` command (chdir) cannot be implemented as an external. It must be a shell built-in in order to be useful. (That's because it changes the shell's own process state). For similar reasons the `read` and `export` and `set` commands must also built-ins. – Jim Dennis Apr 04 '10 at 20:06

score 1 · Answer 4 · answered Apr 04 '10 at 00:35

In most UNIX shells (csh, bash, zsh) aliases are a form of expansion. Thus they are not parsed like functions. Any word in the interactive input stream which would be processed as a command will be scanned against the list of aliases and a simple string replacement will be performed (usually before any other forms of expansion).

If you need to process arguments then you want to define a function which is parsed and processed rather than simply being expanded like a macro.

help with using alias in bash shell

4 Answers4