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Gmail’s SMTP service is widely used for automated mail sending, but it enforces strict rate limits to prevent abuse. Understanding these limits is critical when building mail applications or batch sending systems. Official Rate Limits Google’s official documentation on sending limits is at https://support.google.com/mail/answer/22839. The key constraints are: 500 recipients per day maximum: Sending to…
The “rtnetlink answers: File exists” error typically occurs when restarting network interfaces on Linux, particularly after switching from DHCP to static IP configuration. This happens because the kernel’s routing table has stale entries that conflict with the new configuration you’re trying to apply. Why This Error Occurs When you change network settings and restart the…
When processing delimited data in Bash, you often need to drop the last N fields from each line without knowing the total field count. The naive cut -d’.’ -f1 approach fails immediately when field counts vary. Given input like: systemd.3.gz systemd.mount.3.gz systemd.mount.f.3.gz You want to remove the last 2 fields (.3.gz) to get: systemd systemd.mount…
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…
Vim is fast by default, but plugins can introduce noticeable lag during startup or while editing. Finding the culprit requires systematic profiling of both startup time and runtime behavior. Profile Vim startup time The quickest way to identify slow plugins is to measure how long Vim takes to initialize: vim –startuptime profile.log This creates a…
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…
EPS (Encapsulated PostScript) files are vector graphics commonly used in academic papers, technical documentation, and professional publishing. If you need to modify an EPS file, you have several options depending on your workflow and the complexity of edits required. Using Inkscape Inkscape is the most straightforward tool for editing EPS files on Linux. It’s a…
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…
VirtualBox on Fedora reports “The vboxdrv kernel module is not loaded” when you try to launch it, even though the virtualbox and kernel module packages are installed. This typically happens on systems with UEFI Secure Boot enabled, which requires kernel modules to be cryptographically signed. Check if the module is loaded First, verify whether the…
Network bonding aggregates multiple network interfaces into a single logical interface, providing redundancy, load balancing, or increased throughput. The method you use depends on your distribution and whether you’re managing a desktop, workstation, or server environment. NetworkManager (Desktop and Some Servers) NetworkManager is the easiest approach for most distributions. Create a bond with a single…
Systemd’s coredump handler captures process crash dumps by default, which can consume significant disk space on development or test systems. Here’s how to disable or control coredump storage. Quick Solution Edit /etc/systemd/coredump.conf and set: Storage=none Then reload the systemd daemon: systemctl daemon-reload This prevents coredumps from being stored permanently while still logging crash events. Understanding…
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 have an absolute path like /foo/bar/baz.txt and need to split it into its components, Bash provides two essential utilities: dirname and basename. Using dirname and basename The dirname command returns the directory portion of a path, while basename returns just the filename: p=”/foo/bar/baz.txt” dirname “$p” # Output: /foo/bar basename “$p” # Output: baz.txt…
Chrome on Linux sometimes fails to start with the error “Your profile could not be opened correctly.” This typically happens when the browser’s profile database becomes corrupted, often after a crash or unclean shutdown. Quick Fix: Remove Corrupted Web Data The most reliable solution is to delete the corrupted Web Data file from your Chrome…
When you’re managing a Linux server remotely over SSH, determining whether a USB drive has been connected requires checking kernel messages and device listings since you can’t visually inspect the hardware. Check dmesg for USB Detection Events The most reliable method is examining kernel logs with dmesg. When a USB device is detected, the kernel…
On a Linux system, you often need to let regular users mount and unmount specific devices without requiring sudo or the root password. This is common for external drives, USB devices, or secondary internal disks. There are several approaches, each with different security and usability tradeoffs. Using /etc/fstab with the user Option The simplest approach…
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…
Managing a cluster of servers, you’ll want to be notified when they come back online after restarts or unexpected reboots. Email notifications on boot let you track infrastructure changes and catch potential issues early. Using crontab @reboot The simplest approach is a crontab @reboot entry that runs once at startup. This executes before most services…
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…