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Top Forums Shell Programming and Scripting Explaining behaviour of sudo bash "$0" "$@"; Post 303025441 by Corona688 on Friday 2nd of November 2018 11:50:27 AM
Old 11-02-2018
For starters, you almost never need to use $?, a normal if-statement will do. Written this way, you can kind of see the logic. "If not sudo, then ..."

Not sure if it's really a simplification but I'd add >&2, the traditional place for error messages. That way if someone uses this in a stream they can direct data output and error output separately.

You should have an exit after exec, in case the exec fails for whatever reason (i.e. path problems or something).

Then I'd label the section which is always intended to run as root.

Code:
#!/bin/bash

# If we can't run sudo without a password, complain and exit
if ! sudo -n true 2> /dev/null
then
       echo "please run as root" >&2
       echo "haha you have not power here" >&2
       echo "You need to enter password" >&2
       
       # Not sure if you want this or not?  Exits after printing error/warning
       exit 1
fi

# If EUID isn't zero, replace and re-run this script as root using sudo.
if [ "$EUID" -ne 0 ]
then
        exec sudo bash "$0" "$@"
        echo "exec failed" >&2
        exit 1
fi

#########################################
####### The below section always runs as root #########
#########################################

declare commandOutput=$(apt-add-repository multiverse);
if echo "$commandOutput" | grep -q "distribution component is already enabled"; then 
  echo "multiverse repository is already enabled" >&2
fi

The "replace and re-run" bit comes down to how exec really works: It causes the running program to replace itself with what you ask. Whether it succeeds or fails, after an

The >&2's make more likely that these messages get printed to the terminal, where these messages usually belong.


More could probably be done with apt-get, like checking its return value rather than just assuming it operates correctly.

Last edited by Corona688; 11-02-2018 at 12:56 PM..
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COMMAND-NOT-FOUND(1)					    http://en.opensuse.org/Sco					      COMMAND-NOT-FOUND(1)

NAME
command-not-found - A command-not-found handler SYNOPSIS
command-not-found {binary_name} {repository} ARGUMENTS
The following arguments are required: binary_name The name of binary you are looking for. repository The name of repository for search. For most cases, use zypp DESCRIPTION
command-not-found handler is designed to tell users which package contains a missing command. The handler is integrated to bash(1) and zsh(1) shells and is not necessary to call it directly. Just type a name of the command in your favourite shell and you'll get a result. If you consider c-n-f handler useless, just add unset command_not_found_handle to your profile or remove the command-not-found package. Handler doesn't call the command-not-found binary directly, it only prints info about it. If you want to invoke it automatically, just add export COMMAND_NOT_FOUND_AUTO=1 to your bash profile. EXAMPLE
: NORMAL USAGE For example you want to try blender, because you have heard that is an amazing program. So just type blender in shell: $ blender You get the following output: The program 'blender' can be found in the following package: * blender [ path: /usr/bin/blender, repository: zypp (openSUSE 11.1-0) ] Try installing with: sudo zypper install blender bash: blender: command not found SEE ALSO
scout(1) AUTHOR
Pavol Rusnak <stick@gk2.sk> Developer http://gitorious.org/opensus 08/07/2009 COMMAND-NOT-FOUND(1)
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