TOPIC: LINUS TORVALDS
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.
A Practical Linux Administration Toolkit: Kernels, Storage, Filesystems, Transfers and Shell Completion
4th February 2026
Linux command-line administration has a way of beginning with a deceptively simple question that opens into several possible answers. Whether the task is checking which kernels are installed before an upgrade, mounting an NFS share for backup access, diagnosing low disk space, throttling a long-running sync job or wiring up tab completion, the right answer depends on context: the distribution, the file system type, the transport protocol and whether the need is a one-off action or a persistent configuration. This guide draws those everyday administrative themes into a single continuous reference.
Identifying Your System and Installed Kernels
Reading Distribution Information
A sensible place to begin any administration session is knowing exactly what you are working with. One quick approach is to read the release files directly:
cat /etc/*-releaseOn systems where bat is available (sometimes installed as batcat), the same files can be read with syntax highlighting using batcat /etc/*-release. Typical output on Ubuntu includes /etc/lsb-release and /etc/os-release, with values such as DISTRIB_ID=Ubuntu, VERSION_ID="20.04" and PRETTY_NAME="Ubuntu 20.04.6 LTS". Three additional commands, cat /etc/os-release, lsb_release -a and hostnamectl, each present the same underlying facts in slightly different formats, while uname -r reports the currently running kernel release in isolation. Adding more flags with uname -mrs extends the output to include the kernel name and machine hardware class, which on an older RHEL system might return something like Linux 2.6.18-8.1.14.el5 x86_64.
Querying Installed Kernels by Package Manager
On Red Hat Enterprise Linux, CentOS, Rocky Linux, AlmaLinux, Oracle Linux and Fedora, installed kernels are managed by the RPM package database and are queried with:
rpm -qa kernelThis may return entries such as kernel-5.14.0-70.30.1.el9_0.x86_64. The same information is also accessible through yum list installed kernel or dnf list installed kernel. On Debian, Ubuntu, Linux Mint and Pop!_OS the package manager differs, so the command changes accordingly:
dpkg --list | grep linux-imageOutput may include versioned packages, such as linux-image-2.6.20-15-generic, alongside the metapackage linux-image-generic. Arch Linux users can query with pacman -Q | grep linux, while SUSE Enterprise Linux and openSUSE users can turn to rpm -qa | grep -i kernel or use zypper search -i kernel, which presents results in a structured table. Alpine Linux takes yet another approach with apk info -vvv | grep -E 'Linux' | grep -iE 'lts|virt', which may return entries such as linux-virt-5.15.98-r0 - Linux lts kernel.
Finding Kernels Outside the Package Manager
Package databases do not always tell the whole story, particularly where custom-compiled kernels are involved. A kernel built and installed manually will not appear in any package manager query at all. In that case, /lib/modules/ is a useful place to look, since each installed kernel generally has a corresponding module directory. Running ls -l /lib/modules/ may show entries such as 4.15.0-55-generic, 4.18.0-25-generic and 5.0.0-23-generic. A further check is:
sudo find /boot/ -iname "vmlinuz*"This may return files such as /boot/vmlinuz-5.4.0-65-generic and /boot/vmlinuz-5.4.0-66-generic, confirming precisely which versions exist on disk.
A Brief History of vmlinuz
That naming convention is worth understanding because it appears on virtually every Linux system. vmlinuz is the compressed, bootable Linux kernel image stored in /boot/. The name traces back through computing history: early Unix kernels were simply called /unix, but when the University of California, Berkeley ported Unix to the VAX architecture in 1979 and added paged virtual memory, the resulting system, 3BSD, was known as VMUNIX (Virtual Memory Unix) and its kernel images were named /vmunix. Linux inherited vmlinuz as a mutation of vmunix, with the trailing z denoting gzip compression (though other algorithms such as xz and lzma are also supported). The counterpart vmlinux refers to the uncompressed, non-bootable kernel file, which is used for debugging and symbol table generation but is not loaded directly at boot. Running ls -l /boot/ will show the full set of boot files present on any given system.
Examining and Investigating Disk Usage
Why ls Is Not the Right Tool for Directory Sizes
Storage management is an area where a familiar command can mislead. Running ls -l on a directory typically shows it occupying 4,096 bytes, which reflects the directory entry metadata rather than the combined size of its contents. For real space consumption, du is the appropriate tool.
sudo du -sh /varThe above command produces a summarised, human-readable total such as 85G /var. The -s flag limits output to a single grand total and -h formats values in K, M or G units. For an individual file, du -sh /var/log/syslog might report 12M /var/log/syslog, while ls -lh /var/log/syslog adds ownership and timestamps to the same figure.
Drilling Down to Find Where Space Has Gone
When a file system is full and the need is to locate exactly where the space has accumulated, du can be made progressively more revealing. The command sudo du -h --max-depth=1 /var lists first-level subdirectories with sizes, potentially showing 77G /var/lib, 5.0G /var/cache and 3.3G /var/log. To surface the biggest consumers quickly, piping to sort and head works well:
sudo du -h /var/ | sort -rh | head -10Adding the -a flag includes individual files alongside directories in the same output:
sudo du -ah /var/ | sort -rh | head -10Apparent Size Versus Allocated Disk Space
There is a subtle distinction that sometimes causes confusion. By default, du reports allocated disk usage, which is governed by the file system block size. A single-byte file on a file system with 4 KB blocks still consumes 4 KB of disk. To see the amount of data actually stored rather than allocated, sudo du -sh --apparent-size /var reports the apparent size instead. The df command answers a different question altogether: it shows free and used space per mounted file system, such as /dev/sda1 at 73 per cent usage or /dev/sdb1 mounted on /data with 70 GB free. In practice, du is for locating what consumes space and df is for checking how much remains on each volume.
gdu: A Faster Interactive Alternative
Some administrators prefer a more modern tool for storage investigations, and gdu is a notable option. It is a fast disk usage analyser written in Go with an interactive console interface, designed primarily for SSDs where it can exploit parallel processing to full effect, though it functions on hard drives too with less dramatic speed gains. The binary release can be installed by extracting its .tgz archive:
curl -L https://github.com/dundee/gdu/releases/latest/download/gdu_linux_amd64.tgz | tar xz
chmod +x gdu_linux_amd64
mv gdu_linux_amd64 /usr/bin/gduIt can also be run directly via Docker without installation:
docker run --rm --init --interactive --tty --privileged
--volume /:/mnt/root ghcr.io/dundee/gdu /mnt/rootIn use, gdu scans a directory interactively when run without flags, summarises a target with gdu -ps /some/dir, shows top results with gdu -t 10 / and runs without interaction using gdu -n /. It supports apparent size display, hidden file inclusion, item counts, modification times, exclusions, age filtering and database-backed analysis through SQLite or BadgerDB. The project documentation notes that hard links are counted only once and that analysis data can be exported as JSON for later review.
Unpacking TGZ Archives
A brief note on the tar command is useful here, since it appears throughout Linux administration, including in the gdu installation step above. A .tgz file is simply a GZIP-compressed tar archive, and the standard way to extract one is:
tar zxvf archive.tgzModern GNU tar can detect the compression type automatically, so the -z flag is often optional:
tar xvf archive.tgzTo extract into a specific directory rather than the current working directory, the -C option takes a destination path:
tar zxvf archive.tgz -C /path/to/destination/To inspect the contents of a .tgz file without extracting it, the t (list) flag replaces x (extract):
tar ztvf archive.tgzThe tar command was first introduced in the seventh edition of Unix in January 1979 and its name comes from its original purpose as a Tape ARchiver. Despite that origin, modern tar reads from and writes to files, pipes and remote devices with equal facility.
Mounting NFS Shares and Optical Media
Installing NFS Client Tools
NFS remains common on Linux and Unix-like systems, allowing remote directories to be mounted locally and treated as though they were native file systems. Before a client can mount an NFS export, the client packages must be installed. On Ubuntu and Debian, that means:
sudo apt update
sudo apt install nfs-commonOn Fedora and RHEL-based distributions, the equivalent is:
sudo dnf install nfs-utilsOnce installed, showmount -e 10.10.0.10 can list available exports from a server, returning output such as /backups 10.10.0.0/24 and /data *.
Mounting an NFS Share Manually
Mounting an NFS share follows the same broad pattern as mounting any other file system. First, create a local mount point:
sudo mkdir -p /var/backupsThen mount the remote export, specifying the file system type explicitly:
sudo mount -t nfs 10.10.0.10:/backups /var/backupsA successful command produces no output. Verification is done with mount | grep nfs or df -h, after which the local directory acts as the root of the remote file system for all practical purposes.
Persisting NFS Mounts Across Reboots
Since a manual mount does not survive a reboot, persistent setups use /etc/fstab. An appropriate entry looks like:
10.10.0.10:/backups /var/backups nfs defaults,nofail,_netdev 0 0The nofail option prevents a boot failure if the NFS server is unavailable when the machine starts. The _netdev flag marks the mount as network-dependent, ensuring the system defers the operation until the network stack is available. Running sudo mount -a tests the entry without rebooting.
Troubleshooting Common NFS Errors
NFS problems are often predictable. A "Permission denied" error usually means the server export in /etc/exports does not include the client, and reloading exports with sudo exportfs -ar is frequently the remedy. "RPC: Program not registered" indicates the NFS service is not running on the server, in which case sudo systemctl restart nfs-server applies. A "Stale file handle" error generally follows a server reboot or a deleted file and is cleared by unmounting and remounting. Timeouts and "Server not responding" messages call for checking network connectivity, confirming that firewall rules permit access to port 111 (rpcbind, required for NFSv3) and port 2049 (NFS itself), and verifying NFS version compatibility using the vers=3 or vers=4 mount option. NFSv4 requires only port 2049, while NFSv2 and NFSv3 also require port 111. To detach a share, sudo umount /var/backups is the standard route, with fuser -m /var/backups helping identify processes that are blocking the unmounting process.
Mounting Optical Media
CDs and DVDs are less central than they once were, but some systems still need to read them. After inserting a disc, blkid can identify the block device path, which is typically /dev/sr0, and will report the file system type as iso9660. With a mount point created using sudo mkdir /mnt/cdrom, the disc is mounted with:
sudo mount /dev/sr0 /mnt/cdromThe warning device write-protected, mounted read-only is expected for optical media and can be disregarded. CDs and DVDs use the ISO 9660 file system, a data-exchange standard designed to be readable across operating systems. Once mounted, the disc contents are accessible under /mnt/cdrom, and sudo umount /mnt/cdrom detaches it cleanly when work is complete.
Transferring Files Securely and Efficiently
Copying Files with scp
scp (Secure Copy) transfers files and directories between hosts over SSH, encrypting both data and authentication credentials in transit. Its basic syntax is:
scp [OPTIONS] [[user@]host:]source [[user@]host:]destinationThe colon is how scp distinguishes between local and remote paths: a path without a colon is local. A typical upload from a local machine to a remote host looks like:
scp file.txt remote_username@10.10.0.2:/remote/directoryA download from a remote host to the local machine reverses the argument order:
scp remote_username@10.10.0.2:/remote/file.txt /local/directoryCommonly used options include -r for recursive directory copies, -p to preserve metadata such as modification times and permissions, -C for compression, -i for a specific private key, -l to cap bandwidth in Kbit/s and the uppercase -P to specify a non-standard SSH port. It is also possible to copy between two remote hosts directly, routing the transfer through the local machine with the -3 flag.
The Protocol Change in OpenSSH 9.0
There is an important change in modern OpenSSH that administrators should be aware of. From OpenSSH 9.0 onward, the scp command uses the SFTP protocol internally by default rather than the older SCP/RCP protocol, which is now considered outdated. The command behaves identically from the user's perspective, but if an older server requires the legacy protocol, the -O flag forces it. For advanced requirements such as resumable transfers or incremental directory synchronisation, rsync is generally the better fit, particularly for large directory trees.
Throttling rsync to Protect Bandwidth
Even with rsync, raw speed is not always desirable. A backup script consuming all available bandwidth can disrupt other services on the same network link, so --bwlimit is often essential. The basic syntax is:
rsync --bwlimit=KBPS source destinationThe value is in units of 1,024 bytes unless an explicit suffix is added. A fractional value is also valid: --bwlimit=1.5m sets a cap of 1.5 MB/s. A local transfer capped at 1,000 KB/s looks like:
rsync --bwlimit=1000 /path/to/source /path/to/dest/And a remote backup:
rsync --bwlimit=1000 /var/www/html/ backups@server1.example.com:~/mysite.backups/The man page for rsync explains that --bwlimit works by limiting the size of the blocks rsync writes and then sleeping between writes to achieve the target average. Some volume undulation is therefore normal in practice.
Managing I/O Priority with ionice
Bandwidth is only one dimension of the load a transfer places on a system. Disk I/O scheduling may also need attention, particularly on busy servers running other workloads. The ionice utility adjusts the I/O scheduling class and priority of a process without altering its CPU priority. For instance:
/usr/bin/ionice -c2 -n7 rsync --bwlimit=1000 /path/to/source /path/to/dest/This runs the rsync process in best-effort I/O class (-c2) at the lowest priority level (-n7), combining transfer rate limiting with reduced I/O priority. The scheduling classes are: 0 (none), 1 (real-time), 2 (best-effort) and 3 (idle), with priority levels 0 to 7 available for the real-time and best-effort classes.
Together, --bwlimitand ionice provide complementary controls over exactly how much resource a routine transfer is permitted to consume at any given time.
Setting Up Bash Tab Completion
On Ubuntu and related distributions, Bash programmable completion is provided by the bash-completion package. If tab completion does not function as expected in a new installation or container environment, the following commands will install the necessary support:
sudo apt update
sudo apt upgrade
sudo apt install bash-completionThe package places a shell script at /etc/profile.d/bash_completion.sh. To ensure it is loaded in shell startup, the following appends the source line to .bashrc:
echo "source /etc/profile.d/bash_completion.sh" >> ~/.bashrcA conditional form avoids duplicating the line on repeated runs:
grep -wq '^source /etc/profile.d/bash_completion.sh' ~/.bashrc
|| echo 'source /etc/profile.d/bash_completion.sh' >> ~/.bashrcThe script is typically loaded automatically in a fresh login shell, but source /etc/profile.d/bash_completion.sh activates it immediately in the current session. Once active, pressing Tab after partial input such as sudo apt i or cat /etc/re completes commands and paths against what is actually installed. Bash also supports simple custom completions: complete -W 'google.com cyberciti.biz nixcraft.com' host teaches the shell to offer those three domains after typing host and pressing Tab, which illustrates how the feature can be extended to match the patterns of repeated daily work.
Installing Snap on Debian
Snap is a packaging format developed by Canonical that bundles an application together with all of its dependencies into a single self-contained package. Snaps update automatically, roll back gracefully on failure and are distributed through the Snap Store, which carries software from both Canonical and independent publishers. The background service that manages them, snapd, is pre-installed on Ubuntu but requires a manual setup step on Debian.
On Debian 9 (Stretch) and newer, snap can be installed directly from the command line:
sudo apt update
sudo apt install snapdAfter installation, logging out and back in again, or restarting the system, is necessary to ensure that snap's paths are updated correctly in the environment. Once that is done, install the snapd snap itself to obtain the latest version of the daemon:
sudo snap install snapdTo verify that the setup is working, the hello-world snap provides a straightforward test:
sudo snap install hello-world
hello-worldA successful run prints Hello World! to the terminal. Note that snap is not available on Debian versions before 9. If a snap installation produces an error such as snap "lxd" assumes unsupported features, the resolution is to ensure the core snap is present and current:
sudo snap install core
sudo snap refresh coreOn desktop systems, the Snap Store graphical application can then be installed with sudo snap install snap-store, providing a point-and-click interface for browsing and managing snaps alongside the command-line tools.
Increasing the Root Partition Size on Fedora with LVM
Fedora's default installer has used LVM (Logical Volume Manager) for many years, dividing the available disk into a volume group containing separate logical volumes for root (/), home (/home) and swap. This arrangement makes it straightforward to redistribute space between volumes without repartitioning the physical disk, which is a significant advantage over a fixed partition layout. Note that Fedora 33 and later default to Btrfs without LVM for new installations, so the steps below apply to systems that were installed with LVM, including pre-Fedora 33 installs and any system where LVM was selected manually.
Because the root file system is in active use while the system is running, resizing it safely requires booting from a Fedora Live USB stick rather than the installed system. Once booted from the live environment, open a terminal and begin by checking the volume group:
sudo vgsOutput such as the following shows the volume group name, total size and, crucially, how much free space (VFree) is unallocated:
VG #PV #LV #SN Attr VSize VFree
fedora 1 3 0 wz--n- <237.28g 0Before proceeding, confirm the exact device mapper paths for the root and home logical volumes by running fdisk -l, since the volume group name varies between installations. Common names include /dev/mapper/fedora-root and /dev/mapper/fedora-home, though some systems use fedora00 or another prefix.
When Free Space Is Already Available
If VFree shows unallocated space in the volume group, the root logical volume can be extended directly and the file system resized in a single command:
lvresize -L +5G --resizefs /dev/mapper/fedora-rootThe --resizefs flag instructs lvresize to resize the file system at the same time as the logical volume, removing the need to run resize2fs separately.
When There Is No Free Space
If VFree is zero, space must first be reclaimed from another logical volume before it can be given to root. The most common approach is to shrink the home logical volume, which typically holds the most available headroom. Shrinking a file system involves data moving on disk, so the operation requires the volume to be unmounted, which is why the live environment is essential. To take 10 GB from home:
lvresize -L -10G --resizefs /dev/mapper/fedora-homeOnce that completes, the freed space appears as VFree in vgs and can be added to the root volume:
lvresize -L +10G --resizefs /dev/mapper/fedora-rootBoth steps use --resizefs so that the file system boundaries are updated alongside the logical volume boundaries. After rebooting back into the installed system, df -h will confirm the new sizes are in effect.
Keeping a Linux System Well Maintained
The commands and configurations covered above form a coherent body of everyday Linux administration practice. Knowing where installed kernels are recorded, how to measure real disk usage rather than directory metadata, how to attach local and network file systems correctly, how to extract archives and move data securely without disrupting shared resources, how to make the shell itself more productive, how to extend a Debian system with snap packages and how to redistribute disk space between LVM volumes on Fedora converts a scattered collection of one-liners into a reliable working toolkit. Each topic interconnects naturally with the others: a kernel query clarifies what system you are managing, disk investigation reveals whether a file system has room for what you plan to transfer, NFS mounting determines where that transfer will land and bandwidth control determines what impact it will have while it runs.
Generating Git commit messages automatically using aicommit and OpenAI
25th October 2025
One of the overheads of using version control systems like Subversion or Git is the need to create descriptive messages for each revision. Now that GitHub has its copilot, it now generates those messages for you. However, that still leaves anyone with a local git repository out in the cold, even if you are uploading to GitHub as your remote repo.
One thing that a Homebrew update does is to highlight other packages that are available, which is how I got to learn of a tool that helps with this, aicommit. Installing is just a simple command away:
brew install aicommit
Once that is complete, you now have a tool that generates messages describing very commit using GPT. For it to work, you do need to get yourself set up with OpenAI's API services and generate a token that you can use. That needs an environment variable to be set to make it available. On Linux (and Mac), this works:
export OPENAI_API_KEY=<Enter the API token here, without the brackets>
Because I use this API for Python scripting, that part was already in place. Thus, I could proceed to the next stage: inserting it into my workflow. For the sake of added automation, this uses shell scripting on my machines. The basis sequence is this:
git add .
git commit -m "<a default message>"
git push
The first line above stages everything while the second commits the files with an associated message (git makes this mandatory, much like Subversion) and the third pushes the files into the GitHub repository. Fitting in aicommit then changes the above to this:
git add .
aicommit
git push
There is now no need to define a message because aicommit does that for you, saving some effort. However, token limitations on the OpenAI side mean that the aicommit command can fail, causing the update operation to abort. Thus, it is safer to catch that situation using the following code:
git add .
if ! aicommit 2>/dev/null; then
echo " aicommit failed, using fallback"
git commit -m "<a default message>"
fi
git pushThis now informs me what has happened when the AI option is overloaded and the scripts fallback to a default option that is always available with git. While there is more to my git scripting than this, the snippets included here should get across how things can work. They go well for small push operations, which is what happens most of the time; usually, I do not attempt more than that.
And then there was one...
25th August 2025
Even with the rise of the internet, magazine publishing was in rude health at the end of the last century. That persisted through the first decade of this century before any decline began to be noticed. Now, things are a poor shadow of what once used to be.
Though a niche area with some added interest, Linux magazine publishing has not been able to escape this trend. At the height of the flourish, we had the launch of Linux Voice by former writers of Linux Format. That only continues as a section in Linux Magazine these days, one of the first casualties from a general decline in readership.
Next, it was the turn of Linux User & Developer. This came into the hands of Future when they acquired Imagine Publishing and remained in print for a time after that due to the conditions of the deal set by the competition regulator. Once beyond that, Future closed it to stick with its own more lightweight title, Linux Format, transferring some of the writers across to the latter. This echoed what they did with Web Designer; they closed that in favour of .Net.
In both cases, dispatching the in-house publications might have been a better idea; without content, you cannot have readers. In time, .Net met its demise and the same fate awaited Linux Format a few months ago after it celebrated its silver jubilee. There was no goodbye edition this time: it went out with a bang, reminding us of glory days that have passed. The content was becoming more diverse with hardware features getting included, perhaps reflecting that something else was happening behind the scenes.
After all that, Linux Magazine soldiers on to outlive the others. It perhaps helps that it is published by an operation centred around the title, Linux New Media, which also publishes Admin Magazine. Even so, it too has needed to trim things a bit. For a time, there was a dedicated Raspberry Pi title that lives on as a section in Linux Magazine.
It was while sprucing up some of the content on here that I was reminded of the changes. Where do you find surveys of what is available? The options could include desktop environments and Linux distributions as much as code editors, web browsers and other kinds of software. While it is true that operations like Future have portals for exactly this kind of thing, they too have a nemesis in the form of GenAI. Asking ChatGPT may be their undoing as much as web publishing triggered a decline in magazine publishing.
Technology upheaval means destruction as much as creation, and there are occasions when spending quiet time reading a paper periodical is just what you need. We all need time away from screen reading, whatever the device happens to be.
Keeping a file or directory out of a Git or GitHub repository
26th August 2024
Recently, I have begun to do more version control of files with Git and GitHub. However, GitHub is not a place to keep files with log in credentials. Thus, I wanted to keep these locally but avoid having them being tracked in either Git or GitHub.
Adding the names to a .gitignore file will avoid their inclusion prospectively, but what can you do if they get added in error before you do? The answer that I found is to execute a command like the following:
git rm -r --cached [path to file or directory with its name]
That takes it out of the staging area and allows the .gitignore functionality to do its job. The -r switch makes the command recursive, should you be working with the contents of a directory. Then, the --cached flag is what does the removal from the staging area.
While the aforementioned worked for me when I had an oversight, the following is also suggested:
git update-index --assume-unchanged [path to file or directory with its name]
That may be working without a .gitignore file, which was not how I was doing things. Nevertheless, it may have its uses for someone else, so that is why I include it above.
Fixing an Ansible warning about boolean type conversion
27th October 2022
My primary use for Ansible is doing system updates using the inbuilt apt module. Recently, I updated my main system to Linux Mint 21 and a few things like Ansible stopped working. Removing instances that I had added with pip3 sorted the problem, but I then ran playbooks manually, only for various warning messages to appear that I had not noticed before. What follows below is one of these.
[WARNING]: The value True (type bool) in a string field was converted to u'True' (type string). If this does not look like what you expect, quote the entire value to ensure it does not change.
The message is not so clear in some ways, not least because it had me looking for a boolean value of True when it should have been yes. A search on the web revealed something about the apt module that surprised me.: the value of the upgrade parameter is a string, when others like it take boolean values of yes or no. Thus, I had passed a bareword of yes when it should have been declared in quotes as "yes". To my mind, this is an inconsistency, but I have changed things anyway to get rid of the message.
Resolving VirtualBox Shared Folders problems in Fedora 32 through a correct Guest Additions installation
26th July 2020
While some Linux distros like Fedora install VirtualBox drivers during installation time, I prefer to install the VirtualBox Guest Additions themselves. Before doing this, it is best to remove the virtualbox-guest-additions package from Fedora to avoid conflicts. After that, execute the following command to ensure that all prerequisites for the VirtualBox Guest Additions are in place before mounting the VirtualBox Guest Additions ISO image and installing from there:
sudo dnf -y install gcc automake make kernel-headers dkms bzip2 libxcrypt-compat kernel-devel perl
During the installation, you may encounter a message like the following:
ValueError: File context for /opt/VBoxGuestAdditions-<VERSION>/other/mount.vboxsf already defined
This is generated by SELinux, so the following commands need to be executed before repeating the installation of VirtualBox Guest Additions:
sudo semanage fcontext -d /opt/VBoxGuestAdditions-<VERSION>/other/mount.vboxsf
sudo restorecon /opt/VBoxGuestAdditions-<VERSION>/other/mount.vboxsf
Without doing the above step and fixing the preceding error message, I had an issue with mounting of Shared Folders whereby the mount point was set up, but no folder contents were displayed. This happened even when my user account was added to the vboxsf group, and it proved to be the SELinux context issue that was the cause.
Trying out a new way to upgrade Linux Mint in situ while going from 17.3 to 18.1
19th March 2017
There was a time when the only recommended way to upgrade Linux Mint from one version to another was to do a fresh installation with back-ups of data and a list of the installed applications created from a special tool.
Even so, it never stopped me doing my own style of in situ upgrade, though some might see that as a risky option. More often than not, that actually worked without causing major problems in a time when Linux Mint releases were more tightly tied to Ubuntu's own six-monthly cycle.
Linux Mint releases now align with Ubuntu's Long Term Support (LTS) editions. This means major changes occur only every two years, with minor releases in between. These minor updates are delivered through Linux Mint's Update Manager, making the process simple. Upgrades are not forced, so you can decide when to upgrade, as all main and interim versions receive the same extended support. The recommendation is to avoid upgrading unless something is broken on your installation.
For a number of reasons, I stuck with that advice by sticking on my main machine with Linux Mint 17.3 instead of upgrading to Linux Mint 18. The fact that I broke things on another machine using an older method of upgrading provided even more encouragement.
However, I subsequently discovered another means of upgrading between major versions of Linux Mint that had some endorsement from the project. There still are warnings about testing a live DVD version of Linux Mint on your PC first and backing up your data beforehand. Another task is ensuring that you are upgraded from a fully up-to-date Linux Mint 17.3 installation.
When you are ready, you can install mintupgrade using the following command:
sudo apt-get install mintupgrade
When that is installed, there is a sequence of tasks that you need to do. The first of these is to simulate an upgrade to test for the appearance of untoward messages and resolve them. Repeating any checking, until all is well, gets a recommendation. The command is as follows:
mintupgrade check
Once you are happy that the system is ready, the next step is to download the updated packages so they are on your machine ahead of their installation. Only then should you begin the upgrade process. The two commands that you need to execute are below:
mintupgrade download
mintupgrade upgrade
After these complete, restart your system. In my case, the process worked well, with only my PHP installation requiring attention. I resolved a clash between different versions of the scripting interpreter by removing the older one, as PHP 7 is best kept for testing. Apart from reinstalling VMware Player and upgrading from version 18 to 18.1, I had almost nothing else to do and experienced minimal disruption. This is fortunate as I rely heavily on my main PC. The alternative of a full installation would have left me sorting things out for several days afterwards because I use a customised selection of software.
Updating Piwik using the Linux Command Line
28th November 2016
Because updating Piwik using its web interface has proved tempestuous, I have decided to update the self-hosted analytics application on an SSH session. The production web servers that I use are hosted on Linux systems, so that is why any commands apply to the Linux or UNIX command line only. What is needed for Windows servers may differ.
The first step is to down the required ZIP file with this command:
wget https://builds.piwik.org/piwik.zip
Once the download is complete, the contents of the ZIP archive are extracted into a new subfolder. This is a process that I carry out in a separate folder to that where the website files are kept before copying everything from the extraction folder in there. Here is the unzip command, and the -o switch turns on overwriting of any previously existing files:
unzip -o piwik.zip
Without the required folder in the web server area to be updated, the next step is to do the actual system update that includes any updates to the Piwik database that you are using. There are two commands that you can use once you have specified the location of your Piwik installation. The second is needed when the first option cannot find where the PHP executable is stored. My systems had something more specific than these because both PHP 5.6 and PHP 7.0 are installed. Looking in /usr/bin was enough to find what I needed to execute in place of PHP below. Otherwise, the command was the same.
./[path to piwik]/console core:update
php [path to piwik]/console core:update
While the upgrade is ongoing, it prompts you to permit it to continue before it goes and modifies the database. This did not take long on my systems, but that depends on how much data there is. Once, the process has completed, you can delete any extraneous files using the rm command.
Compressing a VirtualBox VDI file for a Linux guest
6th June 2016
In a previous posting, I talked about compressing a virtual hard disk for a Windows guest system running in VirtualBox on a Linux system. Since then, I have needed to do the same for a Linux guest following some housekeeping. Because the Linux distribution used is Debian, the instructions are relevant to that and maybe its derivatives such as Ubuntu, Linux Mint and their like.
While there are other alternatives like dd, I am going to stick with a utility named zerofree to overwrite the newly freed up disk space with zeroes to aid compression later on in the process for this and the first step is to install it using the following command:
apt-get install zerofree
Once that has been completed, the next step is to unmount the relevant disk partition. Luckily for me, what I needed to compress was an area that I reserved for synchronisation with Dropbox. If it was the root area where the operating system files are kept, a live distro would be needed instead. In any event, the required command takes the following form, with the mount point being whatever it is on your system (/home, for instance):
sudo umount [mount point]
With the disk partition unmounted, zerofree can be run by issuing a command that looks like this:
zerofree -v /dev/sdxN
Above, the -v switch tells zerofree to display its progress and a continually updating percentage count tells you how it is going. The /dev/sdxN piece is generic with the x corresponding to the letter assigned to the disk on which the partition resides (a, b, c or whatever) and the N is the partition number (1, 2, 3 or whatever; before GPT, the maximum was 4). Putting all this together, we get an example like /dev/sdb2.
Once, that had completed, the next step is to shut down the VM and execute a command like the following on the host Linux system ([file location/file name] needs to be replaced with whatever applies on your system):
VBoxManage modifyhd [file location/file name].vdi --compact
With the zero filling in place, there was a lot of space released when I tried this. While it would be nice for dynamic virtual disks to reduce in size automatically, I accept that there may be data integrity risks with those, so the manual process will suffice for now. It has not been needed that often anyway.