TOPIC: STAT
Grouping directories first in output from ls commands executed in terminal sessions on macOS and Linux
12th February 2026
This enquiry began with my seeing directories and files being sorted by alphabetical order without regard for type in macOS Finder. In Windows and Linux file managers, I am accustomed to directories and files being listed in distinct blocks, albeit within the same listings, with the former preceding the latter. What I had missed was that the ls command and its aliases did what I was seeing in macOS Finder, which perhaps is why the operating system and its default apps work like that.
Over to Linux
On the zsh implementation that macOS uses, there is no way to order the output so that directories are listed before files. However, the situation is different on Linux because of the use of GNU tooling. Here, the --group-directories-first switch is available, and I have started to use this on my own Linux systems, web servers as well as workstations. This can be set up in .bashrc or .bash_aliases like the following:
alias ls='ls --color=auto --group-directories-first'
alias ll='ls -lh --color=auto --group-directories-first'
Above, the --color=auto switch adds colour to the output too. Issuing the following command makes the updates available in a terminal session (~ is the shorthand for the home directory below):
source ~/.bashrc
Back to macOS
While that works well on Linux, additional tweaks are needed to implement the same on macOS. Firstly, you have to install Homebrew using this command (you may be asked for your system password to let the process proceed):
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
To make it work, this should be added to the .zshrc file in your home folder:
export PATH="/opt/homebrew/opt/coreutils/libexec/gnubin:$PATH"
Then, you need to install coreutils for GNU commands like gls (a different name is used to distinguish it from what comes with macOS) and adding dircolors gives you coloured text output as well:
brew install coreutils
brew install dircolors
Once those were in place, I found that adding these lines to the .zshrc file was all that was needed (note those extra g's):
alias ls='gls --color=auto --group-directories-first'
alias ll='gls -lh --color=auto --group-directories-first'
If your experience differs, they may need to be preceded with this line in the same configuration file:
eval "$(dircolors -b)"
The final additions then look like this:
export PATH="/opt/homebrew/opt/coreutils/libexec/gnubin:$PATH"
eval "$(dircolors -b)"
alias ls='gls --color=auto --group-directories-first'
alias ll='gls -lh --color=auto --group-directories-first'
Following those, issuing this command will make the settings available in your terminal session:
source ~/.zshrc
Closing Remarks
In summary, you have learned how to list directories before files, and not intermingled as is the default situation. For me, this discovery was educational and adds some extra user-friendliness that was not there before the tweaks. While we may be considering two operating systems and two different shells (bash and zsh), there is enough crossover to make terminal directory and file listing operations function consistently regardless of where you are working.
Fixing WordPress 502 errors caused by incorrect WP-Optimise plugin permissions
31st August 2025
When I started getting a 502 status error on saving a WordPress post, it naturally was concerning, even if I found that the post was saved in the background. Inspection of the Nginx error log was in order, given that an invalid response was triggering the Bad Gateway message. That revealed that the WP-Optimise plugin was triggering the error when trying to access a location on the server. The cause was having incorrect permissions, which was sorted by something like the following:
chown -R www-data:www-data /var/www/html/wp-content/uploads/wpo
chmod -R 755 /var/www/html/wp-content/uploads/wpo
If it were to happen to you, the location may be different, as mine is for me. What you see above is the default. The chown command is assigning www-data as the owner and group for the specified location, with the -R switch triggering recursion for this action. After that, the chmod command is assigning full permissions for the owner, as well as read and execute for everyone else. All of this is to enable WP-Optimise to update its logs, the failure of which was causing the 502 messages in the first place.
Keeping a graphical eye on CPU temperature and power consumption on the Linux command line
20th March 2025
Following my main workstation upgrade in January, some extra monitoring has been needed. This follows on from the experience with building its predecessor more than three years ago.
Being able to do this in a terminal session keeps things lightweight, and I have done that with text displays like what you see below using a combination of sensors and nvidia-smi in the following command:
watch -n 2 "sensors | grep -i 'k10'; sensors | grep -i 'tdie'; sensors | grep -i 'tctl'; echo "" | tee /dev/fd/2; nvidia-smi"
Everything is done within a watch command that refreshes the display every two seconds. Then, the panels are built up by a succession of commands separated with semicolons, one for each portion of the display. The grep command is used to pick out the desired output of the sensors command that is piped to it; doing that twice gets us two lines. The next command, echo "" | tee /dev/fd/2, adds an extra line by sending a space to STDERR output before the output of nvidia-smi is displayed. The result can be seen in the screenshot below.
However, I also came across a more graphical way to do things using commands like turbostat or sensors along with AWK programming and ttyplot. Using the temperature output from the above and converting that needs the following:
while true; do sensors | grep -i 'tctl' | awk '{ printf("%.2f\n", $2); fflush(); }'; sleep 2; done | ttyplot -s 100 -t "CPU Temperature (Tctl)" -u "°C"
This is done in an infinite while loop to keep things refreshing; the watch command does not work for piping output from the sensors command to both the awk and ttyplot commands in sequence and on a repeating, periodic basis. The awk command takes the second field from the input text, formats it to two places of decimals and prints it before flushing the output buffer afterwards. The ttyplot command then plots those numbers on the plot seen below in the screenshot with a y-axis scaled to a maximum of 100 (-s), units of °C (-u) and a title of CPU Temperature (Tctl) (-t).
A similar thing can be done for the CPU wattage, which is how I learned of the graphical display possibilities in the first place. The command follows:
sudo turbostat --Summary --quiet --show PkgWatt --interval 1 | sudo awk '{ printf("%.2f\n", $1); fflush(); }' | sudo ttyplot -s 200 -t "Turbostat - CPU Power (watts)" -u "watts"
Handily, the turbostat can be made to update every so often (every second in the command above), avoiding the need for any infinite while loop. Since only a summary is needed for the wattage, all other output can be suppressed, though everything needs to work using superuser privileges, unlike the sensors command earlier. Then, awk is used like before to process the wattage for plotting; the first field is what is being picked out here. After that, ttyplot displays the plot seen in the screenshot below with appropriate title, units and scaling. All works with output from one command acting as input to another using pipes.
All of this offers a lightweight way to keep an eye on system load, with the top command showing the impact of different processes if required. While there are graphical tools for some things, command line possibilities cannot be overlooked either.
Saving yourself a reboot: remounting any overlooked volumes in Linux
14th September 2024
Recently, I got things a little out of order when starting up my main Linux system after an absence. Usually, I start up my NAS first so that the volumes get mounted when I start my Linux machine. However, it happened that I near enough started them together. Thus, my workstation completed it startup without having the NAS volumes mounted. A reboot would have sorted this, but there was another way: issuing the command that you see below:
sudo mount -a
This looked in my /etc/fstab file and mounted anything that was missing as long as the noauto option was not set. Because this was executed after the NAS had completed its own boot process, it volumes were not mounted on my system and fully available for what I needed to do next. If I had wanted to see what had been mounted, then I needed to issue the following command instead:
sudo mount -av
In addition to the a switch that triggers the mounting of missing volumes, there is now a v (for verbose) one for telling you what has happened. Needless to say, all this happens only if your /etc/fstab file is set up properly. If you are adding a new volume, and I was not, it does no harm to mount it manually before updating the configuration file. That should catch any errors first.