There are several tools available for extracting images from PDFs on Linux, each with different strengths depending on your use case and the PDF structure. pdfimages (Poppler Utils) The most straightforward approach is using pdfimages from the poppler-utils package: pdfimages document.pdf image This extracts all images and saves them as image-000.ppm, image-001.ppm, etc. By default,…
When trying to mount an encrypted EncFS directory as a normal user, you may encounter this error: $ encfs -s ~/t/.enc ~/t/enc EncFS Password: fuse: failed to exec fusermount: Permission denied fuse failed. Common problems: – fuse kernel module not installed (modprobe fuse) – invalid options — see usage message Even though the same command…
The most common need is collapsing multi-line records into single lines. Here are the practical approaches: Using tr to remove newlines The simplest method removes all newlines: tr -d ‘\n’ < input.txt > output.txt This works well for data without embedded line breaks you want to preserve. For CSV or structured data where you need…
The screen terminal multiplexer can capture window output in several ways. Here are the most practical approaches depending on your use case. Enable logging before starting screen Start a new screen session with the -L flag to log all output to a file: screen -L -S mysession This creates a log file named screenlog.0 in…
HP printers and scanners on Rocky Linux, CentOS, or RHEL require the HPLIP (HP Linux Imaging and Printing) package. This guide covers the complete setup process. Install HPLIP packages Start by installing the core HPLIP packages: sudo dnf install hplip hplip-gui hpijs On older CentOS 7 systems, use yum instead of dnf. HPLIP may prompt…
The tee command by default reads from stdin and writes to both stdout and files. To capture only stderr, you need to explicitly redirect it. Basic stderr redirection to tee The straightforward approach is to redirect stderr to stdout, then pipe to tee: command 2>&1 | tee output.log This captures both stdout and stderr. If…
Spaces in file and directory paths are a common source of rsync failures. When paths contain spaces, the shell interprets them as argument separators unless you properly escape or quote them. Here’s how to handle this correctly. The core issue When rsync receives an unquoted path with spaces, the shell splits it at each space….
Temporary files are essential for any non-trivial Bash script. Whether you’re processing data, staging changes, or handling inter-process communication, you need reliable ways to create uniquely-named files that won’t collide with other processes. Using mktemp The standard and most reliable approach is mktemp, which generates a cryptographically random temporary filename: tmpfile=$(mktemp) echo “Temporary file created…
aria2 is a lightweight, multi-protocol download manager that supports HTTP(S), FTP, BitTorrent, and Metalink protocols. It’s particularly useful for resumable downloads, parallel connections, and command-line automation. Prerequisites You’ll need root or sudo access. This guide covers CentOS 7, CentOS Stream, and Rocky Linux 8+. For older systems still on CentOS 7, package availability may be…
curlftpfs is a FUSE-based filesystem that lets you mount FTP/SFTP servers as local directories. This is useful for treating remote FTP locations like local storage without downloading files individually. Prerequisites FUSE kernel module loaded (usually default on modern systems) Root or sudo access Network connectivity to your FTP server Installation on RHEL/CentOS/Rocky Linux The curlftpfs…
When you create VMs in KVM, they’re typically assigned IP addresses via DHCP. Finding those addresses so you can SSH in requires a few steps. Here are the practical approaches. Using virsh domiflist and ARP The traditional method combines virsh domiflist to get the VM’s MAC address, then looks it up in the ARP table:…
SSHFS isn’t available in the default repositories on most RHEL-based distributions. If you try to install it directly, you’ll get an error: # yum install sshfs No package sshfs available. Error: Nothing to do The package lives in EPEL (Extra Packages for Enterprise Linux), so you need to enable that repository first. Enable EPEL For…
CONFIG_HZ sets the kernel’s internal timer interrupt frequency (measured in Hz). This determines how often the kernel’s scheduler runs and how fine-grained process preemption can be. The default value is typically 250 Hz on most distributions, though some set it to 1000 Hz for lower latency workloads. Higher CONFIG_HZ values (like 1000 Hz) reduce scheduling…
Configuring multiple static IP addresses on a Xen VM is useful for hosting multiple services, SSL certificates, or failover scenarios. The approach depends on your underlying Linux distribution and whether you’re using traditional network configuration or modern network managers. Using ip Command for Immediate Changes The quickest way to add a secondary IP is with…
aclocal is part of GNU Autotools and generates aclocal.m4 files needed by the autoconf build system. It’s typically required when working with projects that use traditional Autotools-based builds. Quick Install sudo dnf install automake The automake package provides aclocal, automake, and related utilities. Verify the Installation After installation, confirm aclocal is available: aclocal –version You…
NFS squashes root access to an anonymous user (typically nobody) by default as a security measure. When a client connects as root, the server remaps that user to an unprivileged account, preventing root from having unrestricted access to exported shares. This can cause permission issues if your application genuinely requires root-level file operations. Using no_root_squash…
PARSEC is a widely-used CPU-bound benchmark suite containing real applications and complex third-party library dependencies. The installation can be challenging due to these external requirements, but following this guide will get you up and running. Prerequisites Before starting, install the required build tools and libraries: sudo apt-get update sudo apt-get install build-essential pkg-config gettext autoconf…
The NAS Parallel Benchmarks (NPB) remain a standard tool for evaluating HPC system performance, though landscape has shifted toward additional metrics like HPCG and memory bandwidth tests. This guide covers installation and basic usage. Prerequisites Before installing NPB, you’ll need: Fortran compiler — gfortran is the standard choice on most systems MPI implementation — OpenMPI…
Different projects and languages have different indentation conventions. Rather than manually adjusting settings each time you switch contexts, you can define custom commands in Vim to toggle between common tab widths quickly. Using Custom Functions and Mappings Add these functions to your ~/.vimrc: function SetTab2() set shiftwidth=2 set tabstop=2 set softtabstop=2 echo “Set tab to…
Grep handles tab characters in a few different ways depending on your needs. Here’s what actually works. Using \t with extended regex The most straightforward approach uses grep’s extended regular expressions (-E flag): grep -E ‘\t’ filename.txt This matches any line containing a literal tab character. The \t escape sequence is interpreted as a tab…