utop is an improved OCaml REPL with line editing, history, context-sensitive completion, and syntax highlighting. While powerful, its key bindings differ from standard GNU readline, which can be jarring if you’re used to standard shell behavior. Getting the key bindings list The simplest way to see all available bindings is to run the #utop_bindings directive…
Trailing spaces and tabs at the end of lines are common annoyances in source code and configuration files. They’re invisible, waste space, and can cause issues with certain tools or version control systems. Here’s how to remove them efficiently. Using sed The most straightforward approach with sed: sed ‘s/[[:space:]]*$//’ your_file > your_file.tmp && mv your_file.tmp…
If you have emails stuck in Evolution’s local directory structure that you want to move to an IMAP account via Thunderbird, you’ll need to convert them to a format Thunderbird can import, then push them to your mail server. Step 1: Prepare Your Evolution Mail Directory Evolution typically stores mail in a Maildir format with…
Xen HVM (Hardware Virtual Machine) guests require a configuration file that defines virtual hardware, networking, and boot parameters. Here are practical examples for common scenarios. Installation Configuration Use this configuration when installing a guest OS from an ISO: name=”10.0.1.235″ vcpus=2 memory=2048 shadow_memory=8 disk=[‘file:/lhome/xen/vm-10.0.1.235/vmdisk0,xvda,w’, ‘file:/lhome/Linux-x86_64-DVD.iso,xvdc:cdrom,r’] vif=[‘bridge=xenbr0′] kernel=’/usr/lib/xen/boot/hvmloader’ builder=’hvm’ device_model=’/usr/lib64/xen/bin/qemu-dm’ vnc=1 vnclisten=”0.0.0.0″ vncpasswd=’your-secure-password’ on_reboot=’restart’ on_crash=’restart’ Key points…
When deprovisioning Linux VMs in public cloud environments, disk blocks may be reallocated to other customers if the provider doesn’t properly wipe storage. This is a legitimate concern for security audits, compliance validation, and understanding data exposure risks. Quick Recovery Method The most straightforward approach uses dd and strings to extract readable data from block…
You have an LVM physical volume (PV) you need to remove from a volume group (VG), but the data needs to be preserved and moved to other available PVs. This is a straightforward but important operation that requires careful execution. Prerequisites Before starting, verify: The VG has sufficient free space on remaining PVs to accommodate…
Vim’s default OCaml indentation is limited and doesn’t handle the language’s syntax well. You’ll want to use ocp-indent, a dedicated indentation tool built specifically for OCaml that understands the language’s scoping and structure rules. Installing ocp-indent First, install the tool via OPAM (OCaml Package Manager): opam install ocp-indent If you don’t have OPAM installed, install…
Linux gives you top and htop to monitor CPU and memory by process, but network traffic is different. You need specific tools designed to show which processes are consuming bandwidth. Here are the practical options. nethogs nethogs remains the most straightforward tool for real-time network usage per process: sudo nethogs It displays incoming and outgoing…
There are times when you need direct access to a DomU’s disk from Dom0—for recovery, backup, or maintenance. This is straightforward with Xen’s block device tools, though the commands have evolved depending on your Xen version. Attaching the Disk The method depends on which Xen toolstack you’re using. With xl (Xen 4.1+, recommended): xl block-attach…
When a program appends data to a file, you need to know how much space remains on the partition containing that file. This determines whether the file can grow or if you’re about to hit a capacity limit. Quick answer To find available space for a file, use df: df -B1 /mnt/logs/app-log.log | tail -1…
When you need to execute a system command and capture its output in C, popen() is the standard approach. Unlike system(), which just runs a command, popen() gives you a file stream connected to the command’s stdout or stdin. Basic Usage The popen() function signature is: FILE *popen(const char *command, const char *type); The type…
When you need to format an integer with leading zeros in bash, printf is the standard approach. This is useful for generating zero-padded IDs, filenames, or any formatted output. Using printf The basic syntax mirrors C’s sprintf: n=42 str=$(printf “%08d” “$n”) echo “$str” # Output: 00000042 Here, %08d means: %d — format as decimal integer…
A hard reset (also called a force restart) clears the device’s RAM and stops any stuck processes without erasing your content or Amazon account data. It’s the first troubleshooting step for freezing, unresponsive screens, or software glitches. Basic Hard Reset Steps Locate the power button on your device (usually on the bottom edge or side,…
Converting LaTeX documents to HTML is useful for web publishing. Two main tools handle this conversion effectively: htlatex and latex2html. Both produce valid HTML output, though they have different strengths and limitations. Using htlatex htlatex is part of the tex4ht package and is generally more robust for modern LaTeX documents. Installation: On Fedora/RHEL: sudo dnf…
You have several options for converting HTML files to plain text, each with different strengths depending on your use case. html2text The most straightforward tool is html2text, available on most distributions: html2text input.html The converted text prints to stdout. Redirect to a file if needed: html2text input.html > output.txt Install it via your package manager:…
By default, ibus isn’t automatically started on Fedora with Cinnamon. You might try launching the daemon manually: ibus-daemon This starts the ibus service and adds an icon to your system tray, but you’ll find that Chinese input doesn’t work even when enabled through the tray icon. The missing piece is integration with Cinnamon’s input method…
The Unix epoch (January 1, 1970 00:00:00 UTC) is the standard reference point for timestamps across Linux systems. When you need to convert a timestamp like 1349361711.169942 into a readable date, the date command is your primary tool. Basic Conversion The simplest approach uses date with the @ prefix: date -d @1349361711.169942 Output: Thu Oct…
GDM (GNOME Display Manager) can cause compatibility issues with Cinnamon, particularly around graphics rendering and session management. LightDM is a lightweight alternative that works better with Cinnamon and other desktop environments that don’t depend on GNOME’s ecosystem. Install LightDM First, install LightDM and the GTK greeter if not already present: sudo dnf install lightdm lightdm-gtk…
If you need to remove excess white space or trim margins from PDF files, several graphical tools can handle this on Linux. Here are the most practical options. Krop Krop is a straightforward tool specifically designed for PDF cropping. It lets you define crop regions visually and apply them to single pages or entire documents….
You sometimes need to know whether your shell is running inside screen or tmux. The most straightforward approach is checking the TERM environment variable. Using TERM When screen starts a shell, it sets TERM=screen by default: [user@host ~]$ echo $TERM screen Compare this to a normal terminal session: [user@host ~]$ echo $TERM xterm-256color The TERM…