Unix Commands reference data
Common Unix/Linux shell commands and their usage.
Topic guide
What Unix Commands covers
Unix-command reference data collects the tools that make the shell productive: file and process commands, text processors such as grep, sed and awk, networking utilities, package managers, git for version control and the conventions of shell scripting. The commands are decades old and stable, but their flags differ between GNU/Linux, BSD and macOS, and shell syntax differs between bash, zsh and POSIX sh. Many everyday tasks reduce to composing small commands with pipes. The commands here are the common forms; always read the manual page for the system actually in use.
Key ideas
- Pipe
- The | operator connects one command's output to the next one's input, building pipelines from small tools.
- Exit status
- Every command returns a number: 0 for success and non-zero for failure. Scripts branch on it and set -e makes a failure stop the script.
- Standard streams
- Standard input, output and error (file descriptors 0, 1 and 2), which can be redirected with <, > and 2>.
- Globbing vs regex
- The shell expands wildcards such as *.txt before the command runs; grep, sed and awk interpret regular expressions themselves.
- Quoting
- Single quotes prevent all expansion, double quotes allow variable expansion, and unquoted variables are split on whitespace, a common source of bugs.
- Permissions
- Files carry read, write and execute bits for owner, group and others, set with chmod and shown by ls -l.
- POSIX vs GNU
- POSIX defines portable behavior; GNU tools add extensions (such as sed -i without a suffix) that BSD and macOS may not support.
Common pitfalls
- Running destructive commands (rm -rf, git reset --hard, git clean) without checking the target and having a backup.
- Parsing ls output or leaving variables unquoted, which breaks on filenames with spaces.
- Assuming GNU flags work on macOS or BSD; check the manual page or use portable forms.
- Using sed -i or in-place edits without a backup suffix on files you cannot recover.
Using it from an agent
- Show the exact command and explain each flag; state the shell and OS assumptions.
- Prefer a dry run (echo, -n, --dry-run) or a preview before destructive commands, and warn clearly about irreversible effects.
- Quote variables and paths in examples to model safe habits.
Start with: Git Essential Commands · Unix File Operation Commands
Datasets in Unix Commands
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AWK Reference
Essential AWK commands, built-in variables, and common patterns.
16 entries -
Git Essential Commands
Common Git commands for everyday version control workflows.
36 entries -
Git Recovery and Inspection Workflows
Recoverable Git workflows for finding commits, restoring selected files, and undoing shared changes.
10 entries -
Safer Bash File and Process Patterns
Bash patterns for filenames, temporary files, pipelines, and exit status, with portability boundaries.
10 entries -
Sed Reference
Common sed commands, substitutions, and flags.
16 entries -
Shell Scripting Guide (Bash)
Comprehensive reference for Bash shell scripting: variables, control flow, functions, error handling, debugging, and best practices.
8 entries -
Unix File Operation Commands
Common Unix commands for file and directory operations: ls, find, grep, awk, sed, and tar with examples and usage notes.
21 entries -
Unix Networking Commands (curl, wget, netstat, ss, nmap, dig, ping, traceroute)
Network diagnostics and data transfer: curl/wget (HTTP), netstat/ss (socket stats), nmap (port scanning), dig (DNS), ping/traceroute (connectivity).
8 entries -
Unix Process & System Management Commands
Essential Unix commands for monitoring and managing processes and system resources.
10 entries -
Unix Text Processing Commands (grep, sed, awk, cut, sort, uniq)
Essential text manipulation tools: pattern searching (grep), stream editing (sed), text processing language (awk), field extraction (cut), sorting (sort), duplicate removal (uniq).
8 entries -
Unix/Linux Package Management (apt, yum, dnf, brew, pacman)
Package managers across distributions: Debian/Ubuntu (apt), RHEL/Fedora (yum/dnf), macOS (brew), Arch (pacman). Installation, removal, repository management.
6 entries
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