Bash script using sed & awk

gcclinux · April 21, 2020, 4:21pm

Hello,

I am trying to create a snap package that is based on a bash script but it used many systems tools like sed, awk, tar, OpenSSL, etc

Is there a possibility to create a snap package that executes or allows to execute a bash script that also interacts with different tools like the above mentioned?

Many Thanks

ppd · April 21, 2020, 4:38pm

As long as you ship the dependencies (sed, awk…) in your snap, you can use them in the bash script without a problem. See stage-packages in snapcraft.yaml for shipping packages not included in the base snap: https://snapcraft.io/docs/build-and-staging-dependencies

gcclinux · April 22, 2020, 6:06am

Thank you I will try it. If you have any example of how to include that I’ll do the rest

jamesh · April 22, 2020, 6:13am

You should have access to many of the core command line utilities from the base snap (core or core18) without having to ship your own copy.

Here’s what the base AppArmor template allows:

github.com

snapcore/snapd/blob/006427793cc968cff37ee51ba68beae27520dde0/interfaces/apparmor/template.go#L149-L268


# Common utilities for shell scripts
/{,usr/}bin/arch ixr,
/{,usr/}bin/{,g,m}awk ixr,
/{,usr/}bin/base32 ixr,
/{,usr/}bin/base64 ixr,
/{,usr/}bin/basename ixr,
/{,usr/}bin/bunzip2 ixr,
/{,usr/}bin/bzcat ixr,
/{,usr/}bin/bzdiff ixr,
/{,usr/}bin/bzgrep ixr,
/{,usr/}bin/bzip2 ixr,
/{,usr/}bin/cat ixr,
/{,usr/}bin/chgrp ixr,
/{,usr/}bin/chmod ixr,
/{,usr/}bin/chown ixr,
/{,usr/}bin/clear ixr,
/{,usr/}bin/cmp ixr,
/{,usr/}bin/cp ixr,
/{,usr/}bin/cpio ixr,
/{,usr/}bin/cut ixr,

This file has been truncated. show original

So you can assume that awk, sed, and openssl are available.

gcclinux · April 22, 2020, 6:57am

Thank you this is exactly what I was looking for

devtoolmaker · April 5, 2023, 12:57pm

how to use this? I’m getting my head around stagePackages syntax. Do I add these to stagePackages as

-   /{,usr/}bin/dd ixr,
-  /{,usr/}bin/diff{,3} ixr

Or do I simply add following in stagePackages list

- dd
- diff

ogra · April 5, 2023, 1:08pm

the apparmor rules mean that you have full access to these binaries from the base snap (i.e. core20 or core22) … since your app will use this as the rootfs in your execution environment at runtime, there is nothing you need to do, you can just use /bin/dd or /bin/diff directly without having them in stage-packages at all …

devtoolmaker · April 5, 2023, 1:50pm

Tried with base core18, I get xprop not found. This was the bash command which I used for this testing.

ogra · April 5, 2023, 1:55pm

Well, indeed, only what is on the above list is available… other bits will still need to be staged, xprop is not in the apparmor list linked above nor is it even in the base snaps…

devtoolmaker · April 5, 2023, 3:20pm

got it. I do not fully understand the syntax for stagePackages, how should I add these additional commands

-   /{,usr/}bin/xprop ixr,

OR

-   xprop

ogra · April 5, 2023, 4:45pm

$ apt-file search bin/xprop
x11-utils: /usr/bin/xprop

so you want to stage the x11-utils package …

(stage-packages always only list debian packages from the ubuntu archive, so if you look for some binary you need to find the package name, apt-file is a good tool for this)

devtoolmaker · April 7, 2023, 8:25am

I added x11-utils in stage packages list, I still get the same error - xprop not found

ogra · April 7, 2023, 10:01am

How exactly do you call it ? Note that it will live in $SNAP/usr/bin, this is also added automatically to your PATH variable inside the snap execution environment at runtime… so you should either call it without any path as xprop or with the full path including $SNAP… if your app hardcodes /usr/bin as the call to xprop, you can use a layout to map it to that location.

devtoolmaker · April 7, 2023, 11:46am

I call it without any path i.e xprop. My bash file looks like this

#!/bin/bash
xprop .....

devtoolmaker · April 8, 2023, 5:07pm

@ogra I have tried this multiple time, the issue persists. How do we debug this issue? Is there a way to read metadata of the packaged snap to compare if the package does have the stagePackages we included?