Common UNIX Commands and Utilities: Practical Reference for DevOps and Sysadmin Work

UNIX command-line literacy is foundational for DevOps and operations work, from inspecting logs and managing files to troubleshooting processes and automating recurring tasks. This revised guide turns the original command list into a practical reference you can use during daily terminal work.

Originally published on 2011-01-05; fully revised and updated.

Find commands quickly with built-in documentation

When you do not remember the exact command name, use man -k with a keyword. Then open the manual page for the command you want. GNU tools may also include additional info documentation.

man -k tape
man tar
man csh
info ls
history | tail -20

A safe workflow for using unfamiliar commands

flowchart TD
    A[Need a command] --> B[Search with man -k keyword]
    B --> C[Read man or info page]
    C --> D[Run on test file or test path]
    D --> E{Output expected}
    E -- no --> F[Refine options and retry]
    F --> C
    E -- yes --> G[Automate with script cron or alias]
    G --> H[Use in production task]

UNIX command groups at a glance

For password changes with passwd, follow strong password guidance (original external reference): strong password practices.

C-shell control keys, symbols, and job control

The original article is C-shell oriented in several sections. If you use Bash or Zsh, behavior and key bindings may differ. Also see the linked reference for shell-special filename characters: special characters to avoid in filenames.

Terminal control characters (C-shell)

Special symbols and I/O operators

sleep 300 &
jobs
fg %1
grep 'ERROR' app.log | tee errors.log
sort app.log > sorted.log
wc -l < sorted.log
./rotate-logs.sh >> ops.log 2>&1Code language: HTML, XML (xml)

File, directory, and disk operations

pwd
ls -al
mkdir -p archive/2026
cp app.log archive/2026/
mv archive/2026/app.log archive/2026/app.log.1
find archive -name '*.log*' -type f
du -sh archive
df -hCode language: JavaScript (javascript)

Display, compare, and inspect file contents

head -n 20 /var/log/syslog
tail -n 50 /var/log/syslog
grep -n 'ERROR' app.log
diff -u old.conf new.conf
wc -l app.log
file /bin/ls
strings /bin/ls | headCode language: JavaScript (javascript)

Networking and remote transfer commands

ssh devops@example-host
scp release.tgz devops@example-host:/tmp/
sftp devops@example-host
host example.comCode language: CSS (css)

Text processing, editors, and programming tools

cut -d',' -f1 users.csv | sort
awk '{print $1, $3}' metrics.txt
sed 's/ERROR/WARN/g' app.log > app.log.rewritten
gcc -o hello hello.c
makeCode language: JavaScript (javascript)

Legacy and environment-specific utilities from the original list

• Kerberos commands: kinit, kdestroy
• Email and bulletin tools: mailx, msgs, uuencode, uudecode, rn
• X Window clients: xterm, xauth, xload, xman, xdvi, gv
• TeX toolchain: tex, latex, dvips, latex2html
• Tape/archive operations: mt, dd, tar, ltf
• Scientific/programming libraries and tools listed: lapack, dbm, xdr, netcdf, f77, f2c

Best practices and common pitfalls

• Use man (and man -k) before running unfamiliar commands on production paths.
• Prefer ssh, scp, and sftp over plaintext protocols like telnet and ftp.
• Be careful with destructive commands (rm, mv, dd); test on sample data first.
• Verify which shell you are in; C-shell behavior can differ significantly from Bash/Zsh.
• Use redirection and logging deliberately so command output is auditable (>>, tee, 2>&1).
• Expect command availability to vary across UNIX/Linux environments, especially for legacy tools.

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.