How to add a script call to a linux command?

Question

I want to add in my linux system a script call to the ls command. This script should be executed each time the user execute the ls command.

I tried 2 solutions but both are limited:

1) Using alias

alias ls="/root/myscript.sh; ls"

But this solution is limited because the user can call ls via a variable in this way

var="ls"
$var

see this link for more details

2) Using function

I create a function with the name ls:

ls() { /root/myscript.sh; /bin/ls $@ }

But this solution is limited because the user can call ls in this way:

/bin/ls

Are there another solution?

To avoid recursion, change your function to ls() { /root/myscript.sh; command ls "$@"; } — glenn jackman
– glenn jackman, Commented Nov 28, 2014 at 18:05

Eun · Accepted Answer · 2014-11-28 16:52:57Z

1

You could always rename /bin/ls to /bin/something and create a shell script for /bin/ls and call the original there.

But be warned this can easly brick your system.

answered Nov 28, 2014 at 16:52

Eun

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1 Comment

glenn jackman Over a year ago

If you do not alter /bin/ls, there is no way to prevent the user from invoking /bin/ls directly.

Iharob Al Asimi · Accepted Answer · 2014-11-28 16:53:36Z

1

You can put a script ls say in ${HOME}/myls/ls and then set the path variable to ${HOME}/myls:$PATH

answered Nov 28, 2014 at 16:53

Iharob Al Asimi

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3 Comments

MOHAMED Over a year ago

same problem of (2). I mean this solution is limited when the user call ls with /bin/ls

Iharob Al Asimi Over a year ago

what are you trying to achieve?

tvCa Over a year ago

Mohamed, you are right, but you're asking as if the person from which you want to prevent running LS directly, knows more about the OS than you do ? If that is the case, copy your custom script to /bin/ls ... if that is the kind of level we are talking here. Don't forget to convert your script into a binary file, and use touch to set the date to the date of what /bin/ls now has, so that it doesn't stand out between the other commands.

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