TOPIC: COMPUTER TERMINAL
Incorporating tmux in a terminal workflow
11th March 2025As part of a recent workstation upgrade and subsequent AI explorations to see what runs on a GPU, I got to use tmux to display two panes within a terminal session on Linux Mint, each with output from a different system monitoring command; one of these was top for monitoring system processes in a more in-depth way. Some of that need has passed, yet I retain tmux and even set to open in a new terminal session by adding the following code to my .bashrc file:
if command -v tmux &> /dev/null && [ -z "$TMUX" ]; then
tmux new
fiThis tests if tmux is installed and that this is not running in an existing tmux session before opening a new tmux session. You can also attach to an existing session or use a new default session if you like. That changes the second line of the above code to this:
tmux attach -t default || tmux new -s default
Wanting to have everything fresh in a new session, I decided against that. While I have gone away from using tmux panes for the moment, there is a cheat sheet that could have uses if I do, and another post elsewhere describes resizing the panes too, which came in very useful for that early dalliance while system monitoring.
Changing tab titles in the macOS Terminal app using the command line
25th December 2024One thing that I have noticed with the macOS terminal app that I have not seen with its Linux counterparts is that the tab titles can get stuck after an SSH session to a remote server. Thus, I decided to see if they could be changed or reset. Handily, a single command will do just that:
echo -ne "\033]1;New Tab Title\007"
In a UNIX shell (BASH, ZSH, etc.), the echo command outputs text, and it is the text that changes a tab title. Here, the -ne options both negate the generation of a newline (which would be the function of the -n switch if used on its own) and interprets the escape characters included in the text (which would be the function of the -e switch if used on its own).
Within the text string \033 is the octal representation of the escape character that initiates the control sequence that follows it. This is ]1;, the Operating System Sequence (OSC) for setting the tab title in this case, more generally the icon and window title in other circumstances. The text New Tab Title should be self-explanatory, while \007 is the octal representation of the bell character (BEL) that terminates the OSC.
Because I wanted to have the current working directory path as the title, I made a small modification to do this dynamically:
echo -ne "\033]1;$(pwd)\007"
It is the $(pwd) portion that does just that, taking the output of the pwd command and adding it into the string. Thus, I see what is open in each tab. That stopped me ending up in the wrong one, and I even added an alias into the .zshrc file to make it easier to invoke. The functionality may be a more general UNIX or Linux feature, though I have not had opportunity or reason to try it just yet.
Another way to supply the terminal output of one BASH command to another
26th April 2023My usual way for sending the output of one command to another is to be place one command after another, separated by the pipe (|) operator, adjusting the second command as needed. However, I recently found that this approach does not work well for docker pull commands until I uncovered another option.
The solution is to enclose the input command in $( ) within the output command. Within the parentheses, any kind of command can be declared and includes anything with piping as part of it. As long as text is being printed to the terminal, it can be fed to the second command and used as required. Thus, you can have something like the following:
docker pull $([command outputting name of image to download])
This approach has helped with other kinds of automation of docker image and container use and deployment because it is so general. There may be other uses found for the approach yet.
Killing a hanging SSH session
20th April 2018My web hosting provider offers SSH access that I often use for such things as updating Matomo and Drupal, together with more intensive file moving than an FTP session can support. However, I have found recently that I no longer can exit cleanly from such sessions using the exit command.
Because this produces a locked terminal session, I was keen to find an alternative to shutting down the terminal application before starting it again. Handily, there is a keyboard shortcut that does just what I need.
It varies a little according to the keyboard that you have. Essentially, it combines the carriage return key with ones for the tilde (~) and period (.) characters. The tilde may need to be produced by the combining the shift and backtick keys on some keyboard layouts, but that is not needed on mine. So far, I have found that the <CR>+~+. combination does what I need until SSH sessions start exiting as expected.
Dropping back to a full screen terminal session from a desktop one in Linux
29th May 2014There are times when you might need to access a full screen terminal from a Linux graphical desktop. For example, I have needed this when installing Nvidia's graphics drivers on Ubuntu or Linux Mint. Another instance occurred on Arch Linux when a Cinnamon desktop update prevented me from opening a terminal window. The full screen command let me install an alternative terminal emulator, with Tech Drive-in's list proving helpful. Similar issues might need fixing on FreeBSD installations. These latter examples happened within VirtualBox, which has special requirements for accessing full screen command line sessions, which I'll explain later.
When running Linux on a physical PC, press CTRL + ALT + F1 to enter a full screen terminal and CTRL + ALT + F7 to return to the graphical desktop. In a Linux VirtualBox guest with a Linux host, these shortcuts affect the host instead. For the guest OS, use [Host Key] + F1 to enter a full screen terminal and [Host Key] + F7 to return to the graphical desktop. The default Host Key is the right CTRL key, unless you've changed it.
X sessions in GNOME and Cinnamon desktop environments support this functionality, but I can't confirm it works with alternatives like Wayland. Hopefully, this feature extends to other setups, as terminal sessions are occasionally needed for system recovery. Such mishaps are thankfully rare and should be virtually non-existent for most users.