[SOLVED] How to call a bash function from an alias

usr345 · 09-20-2022, 11:22 PM

Code:

function hello {
    echo "Hello world"
}

alias hello='?'

evo2 · 09-21-2022, 01:29 AM

You want to make an alias with the same name as the function, and for that alias to call the function? What am I missing here?

chrism01 · 09-21-2022, 01:39 AM

I agree with evo2; you just call the fn directly, no need for an alias as well.

pan64 · 09-21-2022, 01:49 AM

using alias in scripts is not really suggested, but not impossible. See here: https://stackoverflow.com/questions/...n-shell-script
but it is still unclear what do you want to achieve

usr345 · 09-21-2022, 02:01 AM

Ok, let's call it with another name then a function:

Code:

alias helloW='?'

Quote:

Originally Posted by pan64

it is still unclear what do you want to achieve

I want to run several commands with an alias from shell. And inside a function this can be achieved easier.

evo2 · 09-21-2022, 04:16 AM

Quote:

Originally Posted by usr345

I want to run several commands with an alias from shell. And inside a function this can be achieved easier.

Why not call the function from the shell? What is the point of the alias?

usr345 · 09-21-2022, 05:23 AM

Quote:

Originally Posted by evo2

Why not call the function from the shell? What is the point of the alias?

How to do it? I thought the alias is the solution with minimal typing. I solved the task using the following trick:

functions.sh:

Code:

function hello {
    echo "Hello world"
}

# the next line calls the function passed as the first parameter to the script.
# the remaining script arguments can be passed to this function.

$1 $2 $3 $4 $5

.bashrc:

Code:

alias hello='~/functions.sh hello'

Is it possible to create a shorter solution?

pan64 · 09-21-2022, 09:30 AM

I still don't understand it but in general you need to avoid alias in such cases. (would be nice to explain how do you want to use that alias). It is not designed to work in a non-interactive environment

Quote:

Bash aliases are essentially shortcuts that can save you from having to remember long commands and eliminate a great deal of typing when you are working on the command line.

Use functions instead in your shell scripts.

usr345 · 09-21-2022, 10:51 AM

Quote:

Originally Posted by pan64

would be nice to explain how do you want to use that alias).

I have a LUKS encrypted volume, I have to run several commands to mount and unmount it. Here is the unmount function that I have created:

Code:

function closeVault() {
    umount /home/usr345/texmf/tex/latex
    if [ $? != 0 ]; then
        exit
    fi

    umount /dev/mapper/vault
    if [ $? != 0 ]; then
        exit
    fi

    cryptsetup close vault
}

I want to run this function interactively from bash using a short alias like: umntvault.

pan64 · 09-21-2022, 10:55 AM

you can use it as closeVault. But if you want to run it as umntvault you can rename the function or create another function which will just call this one. (or actually you can create an alias for that too:
alias umntvault=closeVault.

evo2 · 09-21-2022, 06:44 PM

Quote:

Originally Posted by usr345

How to do it?

Minimal example. Add the following to your .bashrc (or any file that is sourced by your shell).

Code:

function hello
{
    local name=$1
    echo "hello $name I am a function"
}

Source that file, or get a new login shell, then run the command "hello usr345".

Evo2.

evo2 · 09-21-2022, 06:46 PM

Quote:

Originally Posted by usr345

I have a LUKS encrypted volume, I have to run several commands to mount and unmount it. Here is the unmount function that I have created:

Code:

function closeVault() {
    umount /home/usr345/texmf/tex/latex
    if [ $? != 0 ]; then
        exit
    fi

    umount /dev/mapper/vault
    if [ $? != 0 ]; then
        exit
    fi

    cryptsetup close vault
}

I want to run this function interactively from bash using a short alias like: umntvault.

Make sure the file that contains that function has been sourced and just run "closeVault". No need for an alias.

Evo2.

rnturn · 09-21-2022, 10:21 PM

Quote:

Originally Posted by usr345

Code:

function hello {
    echo "Hello world"
}

alias hello='?'

Put the function in a file, say, "myfuncts". Then source that file as shown below:

Code:

$ cat>myfuncts
function hello {
    echo "Hello world"
}^D
$ source ./myfuncts
$ hello
Hello world

Note, though, that the functions in "myfuncts" may not be available "globally". Try it for yourself and see. But if you're writing scripts, you can put "myfuncts" in a directory that in your PATH ($HOME/bin is a likely place and may already be in your PATH) and source that "myfuncts" file as shown above:

Code:

$ mv ~/myfuncts $HOME/bin
$ cd /tmp
$ source myfuncts
$ hello
Hello world

HTH...

rnturn · 09-21-2022, 10:30 PM

Quote:

Originally Posted by pan64

Use functions instead in your shell scripts.

This ^^^^

OP: Using aliases that are defined at login time work may work just great in the scripts that you run interactively. Eventually, though, you're going to want to run a script as a cron job and those aliases aren't going to be defined in the environment used to the run cron job. The results that are emailed to you will be full of error messages. Unless you also source the aliases definitions in the script that you are running via cron. Just for fun, try running the "hello" alias you've defined as a command under cron. You will get an error message. Using the "normal" commands is self-documenting, too.