Linux command reference: grep, sed, find, curl

This section is the reference manual for everyday Linux commands. Filter a log, find a lost file, archive a directory, query an API: each common task has its command, and each one has its dedicated guide here, concise, focused on the options that actually matter, with testable examples. Intended for an administrator or a DevOps profile who wants a reliable reference at hand rather than a web search every time.

The commands are grouped by use. No need to learn them in order: open the guide you need, and keep this page as the entry point of the command reference module.

What you will learn

Place the twelve commands of the section by use: text, files, web
Choose between grep, sed, awk and cut to process a text stream
Tell apart curl, wget and httpie to talk to an HTTP server
Know where to start when you are new to the command line

Filter and transform text

On Linux, everything is text: logs, configuration files, command output. An administrator therefore spends most of their time filtering, extracting and transforming text streams. These four commands are the foundation: grep to search, sed to replace, awk to process columns, cut to isolate fields. Mastered together, they replace most manual edits.

Each one has its guide: grep to filter lines by pattern, including regular expressions and recursive search, sed to replace, delete or insert without opening an editor, awk to compute on tabular data field by field, and cut to isolate columns or characters.

Search, process and archive files

Beyond text, daily work means locating files, acting in bulk on lists and packaging directories. find walks the tree according to precise criteria, name, size, date; xargs turns a list into arguments for another command; parallel runs jobs in parallel to process large volumes faster; tar archives and compresses a set of files into a single one. This is the toolkit of batch processing.

Each one has its guide: find to walk the tree and act on the result, xargs to build commands from a list, parallel to process many inputs simultaneously, and tar to group and compress files into a single archive.

Query the web and handle JSON

A server constantly talks to the outside world: download a package, test an API, read a response. curl and wget fetch HTTP resources, the first for testing and scripting, the second for robust downloading; httpie offers a readable syntax for APIs; jq filters and reformats the JSON that comes back. Together, they cover application network diagnostics and automation.

Each one has its guide: curl to test an API and script HTTP exchanges, wget to fetch files and pages robustly, even in batches, httpie for a readable, colourised output, and jq to filter, extract and reformat JSON responses.

Where to start

If you are a beginner, two commands pay off immediately: grep to dig through a file or a log, and find to track down what hides in the tree. Then comes the sed and awk pair, which turns these searches into automated processing. The web commands, curl and jq, come in as soon as you touch an API or a deployment script. The rest is looked up as needs arise.

Key points

Linux handles text: grep, sed, awk and cut are its basic toolkit.
find locates files; xargs and parallel act in bulk; tar archives.
curl, wget and httpie talk to the web; jq formats JSON.
These commands chain through pipes, that is where their real power lies.
This page is a map: each command has a dedicated guide, to open when needed.