Category: Ubuntu

Categories
Linux Red Hat Ubuntu

Bash: remove trailing slash from a variable

Suppose you have a variable containing a directorypath:

#!/bin/bash
directorytouse="/home/myhome/whateverdirectory/"

If you try to test in your bash script if the directory exists, then it will fail because of the trailing slash:

if [ ! -d "${directorytouse} ] 
then
    echo -e "directory does not exist!"
fi

The easiest way to remove this / if it is present is to use shell parameter expansion:

if [ ! -d "${directorytouse%/}" ]
then
    echo -e "directory does not exist!"
fi

This will get rid of the trailing slash if there is one. If there is no trailing slash present, then nothing will happen.

Categories
Linux Red Hat Ubuntu

Help, my terminal shows graphical characters instead of normal text

If you have ever used cat or tail to accidentally show a binary file, you will have noticed your terminal show graphical garbage instead of readable text. As shown in the screenshot below:

You will find several suggested fixes on the internet for this, including:

  • type CTRL-C a few times to make sure you are on a new line and then enter ‘reset‘ and tap enter.
  • output the ASCII SI (shift in) character, decimal value 15. This can be entered with CTRL+O and should work if the reset command doesn’t work. Just enter ‘echo CTRL+V CTRL+O’ on the command line
  • enter the command ‘stty sane’, followed by ‘tput rs1’ on the command line.

The only one that worked for me is entering the following (blindly, since you can ‘t read what your are typing) on the terminal prompt:

echo -e "\033c"

A good practice is to define an alias in your startup script with the following command:

alias resetterminal='echo -e "\033c"'

Next time you have this problem, you can then type (blindly) ‘resetterminal’ to fix the problem.

Categories
Linux Red Hat Ubuntu

Vi (or Vim) session no longer responding?

If your Vi or Vim session is hanging and is not responding to anything, then it might be because you pressed CTRL+S accidentally (out of habbit). To fix this, just press CTRL+Q to unblock the session.

Categories
Dell XPS15 Laptop Linux Ubuntu

No wifi or no external monitor on Dell XPS-15

If your wifi card is not available after booting your Dell XPS-15 laptop (with Ubuntu 20.04 or 22.04), or your external monitor refuses to display anything, please try the following:

start up your laptop without your power supply plugged in, connect with wifi, and/or your external monitor and only then plug in your power supply.

This fix works everytime for me.

Categories
Linux Ubuntu

Ubuntu Server – CTRL-ALT-DEL

If you press CTRL-ALT-DEL on a Ubuntu Server the server will be shut down without asking any confirmation or password. This is of course not a good idea.

To disable this, enter the following commands as root:

systemctl mask ctrl-alt-del.target
systemctl daemon-reload