When passwordless SSH authentication fails despite proper key setup, start by checking the SSH daemon logs to identify the actual problem. Checking SSH Logs The SSH daemon logs are your primary diagnostic tool: sudo tail -f /var/log/auth.log # Debian/Ubuntu sudo tail -f /var/log/secure # RHEL/CentOS/Fedora sudo journalctl -u ssh -f # systemd-based systems Watch the…
Keeping home directories synchronized across multiple machines is a practical problem for anyone managing several laptops, workstations, or servers. You need something that handles bidirectional sync, understands which changes win when conflicts occur, and doesn’t destroy data on either side. Unison Unison remains a solid choice for this. It’s a bidirectional file synchronizer that works…
IBus is the default input method framework on many Linux distributions, but Chrome and Chromium-based browsers have historically struggled with proper IBus integration. Other applications like Thunderbird, Firefox, and GNOME applications typically work fine, which points to Chrome’s specific handling of input methods. Root Causes Chrome doesn’t use the standard Linux input method pipeline that…
Dropbox on Linux has two main approaches: the official daemon (headless) or the sync client with GUI. Which you choose depends on your use case. Official Dropbox Daemon (Recommended for Servers) The daemon is lightweight and works well on headless systems. Download and extract it: cd ~ && wget -O – “https://www.dropbox.com/download?plat=lnx.x86_64” | tar xzf…
When working with relative paths in Linux, you often need the absolute path for scripting, logging, or passing to other programs. Several tools can resolve this, each with different strengths. Using readlink The readlink command is the traditional tool for this job. The -f flag follows symlinks and resolves the path to its absolute form:…
When you first use git on a machine, you’ll need to configure your identity. Git uses these credentials to author your commits: git config –global user.name “Your Name” git config –global user.email you@example.com These settings are stored in ~/.gitconfig and apply to all repositories on your system. Verifying your configuration Check what you’ve set: git…
The conventional wisdom that smaller code is always better has been thoroughly invalidated on modern processors. A statement from kernel development circles captured this well: for performance-critical paths like interrupt handlers, large-but-correctly-aligned-and-optimized code consistently outperforms byte-packed alternatives. Consider this comparison: mov eax, [foo] add eax, 1 mov [foo], eax versus: inc [foo] The three-instruction sequence…
Archiving or copying a 1TB sparse file containing only 32MB of actual data is impractical with naive approaches—you’ll waste time and I/O bandwidth copying zeros. The solution is using SEEK_HOLE and SEEK_DATA flags with lseek(), which allow tools to skip over hole regions entirely. How SEEK_HOLE and SEEK_DATA work The Linux kernel provides two additional…
If you suspect a disk has bad blocks, use the badblocks utility to scan for them. This tool probes a device (usually a disk partition) and reports which blocks are unreliable or unreadable. Basic Usage badblocks /dev/sda1 This scans /dev/sda1 from the first block to the last block on the device. Common Options -s: Show…
MATE is a continuation of GNOME 2, maintained by the MATE Desktop Environment project. It’s included in Fedora’s official repositories and is a supported desktop option. Install MATE Desktop MATE is available as a desktop environment group in Fedora 41’s repositories. Install the base desktop with: sudo dnf install @mate-desktop The @mate-desktop group installs the…
When you need to verify that two Linux systems can communicate over a specific protocol and port, you have several solid options. Let’s cover the most practical approaches. Using nc (netcat) The nc command remains a reliable choice for quick connectivity tests. It’s widely available and requires no special setup. TCP connection test To listen…
LVM (Logical Volume Management) abstracts physical storage into logical volumes, giving you flexibility to resize filesystems, snapshot data, and manage disk space without downtime. It sits between your physical disks and the filesystems you mount. The three core LVM concepts are: Physical Volumes (PVs): Physical disks or disk partitions Volume Groups (VGs): Collections of PVs…
A hard link is an additional directory entry pointing to the same inode as the original file. Unlike symbolic links, hard links share the same inode number and have identical permissions, ownership, and content. To find all hard links to a file, you need to locate every directory entry with the same inode. Using find…
When you mmap() a range larger than your system’s total physical memory plus swap, the kernel normally reserves swap space to back the mapping. If that reservation would exceed available swap, mmap() fails with ENOMEM. The MAP_NORESERVE flag lets you bypass this reservation requirement. Understanding the Default Behavior By default, when you call mmap() with…
Evolution is a full-featured personal information management suite that handles email, contacts, calendars, and tasks. It includes enterprise features like native Microsoft Exchange support and integrates deeply with GNOME’s ecosystem. To troubleshoot issues, migrate data, back up configurations, or secure your setup, you need to know where Evolution stores everything. Evolution follows the XDG Base…
NFSv4 significantly simplifies network exposure compared to NFSv3. Where NFSv3 requires managing multiple dynamic ports (mountd, statd, lockd), NFSv4 uses only port 111 (rpcbind) and port 2049 (NFS). This makes firewall configuration and port forwarding straightforward. For production environments, consider implementing Kerberos authentication (krb5, krb5i, or krb5p) instead of relying solely on network-based access control….
When you need to display data on point-of-sale receipts that isn’t available in the standard receipt designer, you’ll need to create a custom field. This involves work in both Dynamics 365 (the backend) and the Retail SDK (the POS application layer). This walkthrough covers adding a custom field—using item barcodes as an example—though the pattern…
This post covers .NET Core 2.1, which released in May 2018. Some of the predicted features below didn’t materialize as described; we’ll clarify what actually landed versus what was speculated. What is .NET Core? .NET Core is Microsoft’s open-source, cross-platform runtime for building applications in C#, F#, and Visual Basic. Unlike the monolithic .NET Framework…
If you’re working on Windows but need to interact with Linux systems, you’ll need reliable remote access tools. SSH is the standard—it’s secure, scriptable, and works everywhere. Here’s what actually matters. SSH Clients Windows Terminal + OpenSSH is the baseline for Windows 11. It’s built-in, integrates native SSH without extra installation, and handles key authentication…
Hibernate Envers is a proven auditing framework that automatically tracks changes to JPA entities without cluttering your domain model with logging code. It stores historical data in separate audit tables and lets you query entity states at any point in time. Why Use Hibernate Envers Envers handles the mechanics of change tracking transparently: Audits all…