If you’re stuck at the Ubuntu login screen with errors like “Could not write bytes: Broken Pipe” or “Check Battery State,” the display manager is likely corrupted or misconfigured. This typically indicates a problem with LightDM, Ubuntu’s default display manager since 12.04. Understanding the Problem LightDM (the lightweight X display manager) manages your login session…
Finding and sorting files by modification time across directories is a common task for log rotation, cleanup scripts, and audit purposes. Here are the most practical approaches. Using find with printf (simplest method) The find command with -printf is the fastest and most portable approach: find . -type f -printf ‘%T@ %p\n’ | sort -rn…
When your application fails to bind to a port, you need to identify what’s already using it. This is one of the most common debugging tasks in Linux system administration. Using ss (Modern Approach) The ss command has largely replaced netstat in modern Linux distributions. It’s faster, more efficient, and provides clearer output: ss -ltnp…
When you export a variable in Bash, it becomes available to all child processes spawned from your shell. Sometimes you need to remove that exported status or delete the variable entirely. There are two main approaches depending on what you want to achieve. Remove export status but keep the variable If you want the variable…
When you try to redirect output from a sudo command to a file using >, you’ll hit a permission error: $ sudo echo “echo hello” > /usr/local/bin/hello bash: /usr/local/bin/hello: Permission denied This happens because the shell processes the redirection operator > before sudo runs. The redirection happens in your unprivileged shell context, not as root….
Converting text to lowercase is a common task in shell scripts and command-line workflows. Linux offers multiple approaches, each with different trade-offs in performance, portability, and Unicode handling. Using tr for simple conversions The tr command translates characters and is widely portable across Unix-like systems: echo “HELLO WORLD” | tr ‘[:upper:]’ ‘[:lower:]’ Output: hello world…
GNU Screen is a terminal multiplexer that lets you manage multiple shell sessions within a single window. If you’re new to it, here are the best resources to get up to speed, plus practical tips for getting started. Getting Started with Screen For an introduction to the basics, start with A quick tutorial on screen….
Merging PDFs on Linux is straightforward with several tools available, each suited to different needs. Whether you need a quick command-line merge or want to reorder pages visually, here’s what works best. pdfunite: The Simplest Approach The fastest way to merge PDFs is with pdfunite from poppler-utils: pdfunite file1.pdf file2.pdf file3.pdf output.pdf Install it if…
When a filesystem listed in /etc/fstab fails to mount during boot, the system can hang or drop to an emergency shell, preventing normal startup. This happens because the kernel treats all mount entries equally by default. Non-critical filesystems—network shares, external drives, or optional data partitions—shouldn’t block your entire system from booting. Understanding fstab mount options…
The standard crontab -e command opens an interactive editor, which doesn’t work in automated scripts. To add crontab entries non-interactively, you need to pipe a list of cron jobs directly to crontab -. Basic approach The simplest method reads the existing crontab, appends your new entry, and writes it back: (crontab -l 2>/dev/null; echo “@reboot…
HDFS doesn’t natively support directory-level replication factor inheritance. Even if you set a specific replication factor on a directory and its files, new files created in that directory will default to the cluster’s global dfs.replication setting (typically 3). This limitation can complicate multi-tier storage strategies where you want temporary or low-priority data on fewer replicas…
Finding files that match a pattern is straightforward with ls *string* or find . -name ‘*string*’. But excluding files with a certain string in their filename requires a different approach. Using find with negation The most reliable method is find with the ! (or -not) operator: find . -type f ! -name ‘*string*’ This finds…
Fedora’s default repositories don’t include musl libc, but you have two practical options: install it from a community repository if available, or build from source. Building from source gives you full control and is the most reliable approach across Fedora versions. Option 1: Build from Source (Recommended) Start by installing the build dependencies: sudo dnf…
Deleted photos from your Samsung phone aren’t necessarily gone forever—they remain on disk until overwritten. Here’s how to recover them. Act quickly to preserve data The moment you realize photos are deleted, stop using your phone. Every new photo, message, or app activity risks overwriting deleted data. Turn off WiFi and mobile data to prevent…
LXTerminal may fail to display Chinese characters correctly if fonts aren’t properly configured. This is typically a font availability or configuration issue rather than a terminal limitation. Check Your Font Setup First, verify that Chinese fonts are installed on your system. Install them if needed: Fedora/RHEL: sudo dnf install fonts-noto-cjk Debian/Ubuntu: sudo apt install fonts-noto-cjk…
Xterm doesn’t send Alt key escape sequences by default, which breaks Alt-based keybindings in Vim, Emacs, shell readline, and other applications. Here’s how to fix it across different terminal setups. Xterm Configuration Add this to your ~/.Xresources file: xterm*metaSendsEscape: true Then load the changes and restart xterm: xrdb -merge ~/.Xresources xterm & This tells xterm…
When backing up with rsync, you often need to skip directories like cache/, node_modules/, or .git/ that appear at multiple levels in your directory tree. Listing every instance individually is impractical, but rsync’s exclude patterns handle this elegantly. Basic exclude syntax The simplest approach uses –exclude with a directory name pattern: rsync -avxP –exclude=cache/ /path/to/src/directory/…
When you need to audit disk usage or understand directory structure, counting files in each subdirectory is a common task. This is especially useful when dealing with large directory trees where you need a quick overview of distribution. The Basic Approach The simplest method uses a loop with find and wc: for i in */;…
When you need to change the commit message of a past commit that isn’t HEAD, git commit –amend alone won’t help. You’ll need to use interactive rebase to stop at that commit, amend it, and then continue. Interactive Rebase to Edit a Commit The core approach is git rebase -i with the commit hash. Say…
When working with non-standard C file extensions, Vim’s taglist plugin and filetype detection won’t automatically recognize them. You need to explicitly tell Vim to treat those files as C source. Basic approach Add this to your ~/.vimrc: autocmd BufRead,BufNewFile *.c0 set filetype=c Replace *.c0 with whatever extension you’re using. This tells Vim that any file…