You can retrieve detailed metadata about an S3 object using the aws s3api head-object command. This is useful when you need to check object properties, sizes, modification times, or custom metadata without downloading the entire file. Basic Usage The simplest form queries an object’s metadata: aws s3api head-object –bucket test-hkust –key dir2/fileupload/fb0c6353-a90c-4522-9355-7cd16cf756ff.file.txt This returns output…
By default, xargs appends its input as arguments at the end of the command. This works fine when you need a utility once per item, but becomes problematic when you need to reference the same input multiple times in different positions. The Problem Consider renaming files by appending .bak to each filename. You might try:…
When stop-dfs.sh fails to cleanly terminate DataNode processes, you’re left with orphaned Java processes consuming resources and potentially causing cluster issues. This happens most often after ungraceful cluster shutdowns or when the standard stop script encounters communication problems with specific nodes. Understanding the Problem The typical symptom is stop-dfs.sh reporting that certain nodes have no…
While BIOS settings are the preferred way to disable USB 3.0, you can also force USB 2.0 mode on a running Linux system by manipulating the xHCI controller’s port routing register directly using setpci. How it works Intel xHCI controllers use the XUSB2PR (xHC USB 2.0 Port Routing Register) at offset 0xd0. Setting this register…
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…
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 */;…
Removing version control or build artifact directories across a large directory tree is a common sysadmin task. SVN directories (.svn), Git metadata (.git), or node modules (node_modules) often need to be purged before deployment or archiving. Using find with xargs The most efficient approach combines find with xargs: find ./ -name “.svn” -type d |…
The built-in etags command doesn’t recursively traverse directories by default, but generating TAGS files across your entire project is straightforward with the right tools and setup. Using ctags (Recommended) The simplest approach is ctags with the -e flag, which generates Emacs-compatible TAGS files: ctags -e -R . The -R flag enables recursive traversal. This works…
Finding large files is something you end up doing a lot — disk fills up, you need to track down what’s eating space, or you’re auditing a directory before archiving. The find command handles this cleanly. Basic usage Find all files larger than 500MB under the current directory: find . -type f -size +500M The…
Broken symbolic links accumulate over time and can cause confusion or errors when scripts rely on their targets. Identifying and cleaning them up is a regular maintenance task. Basic approach Use find with the -xtype l test to locate broken symlinks: find /path/to/directory -xtype l The -xtype l flag specifically matches symbolic links that point…
Running your own Python installation on Dreamhost (or similar shared hosting) gives you control over the version, packages, and dependencies without relying on system-wide Python. This is especially useful when you need specific Python versions or packages the hosting provider doesn’t support. Why Use a Custom Python Installation Shared hosting environments typically ship with outdated…
Attachments in WordPress are tied to specific posts through a parent-child relationship stored in the database. This matters more than you’d think — attachment metadata, URLs, and admin filtering all depend on that parent assignment. Sometimes you need to reassign an image or document to a different post, whether because of organizational restructuring, post merging,…
Working in an SVN repository often leaves behind temporary build artifacts, compiled outputs, and editor cache files. Unlike Git’s git clean command, SVN has no built-in cleanup mechanism for untracked files. Using svn st to Identify Untracked Files The svn status command (or svn st) marks untracked files with a ? prefix. You can leverage…