20 advanced Linux command line examples 👇🐧

1/ rsync: Synchronize files & dirs locally or b/n servers efficiently, preserving perms & ownership.

rsync -avz --delete /local/path/ user@remote:/remote/path/

Syncs the contents of /local/path/ to /remote/path/ on remote server, deleting any extraneous files on the destination

2/ awk: A powerful text processing tool, often used for pattern scanning and processing.

ps aux | awk '$3 > 50 {print $1}'

This command lists the usernames of processes consuming more than 50% CPU.

3/ sed: Stream editor for filtering and transforming text.

sed -i 's/old_text/new_text/g' filename

This command replaces all occurrences of old_text with new_text in the filename.

4/ find: Search for files and directories in a directory hierarchy.

find /path/to/search -name "*.log" -type f -mtime +7 -delete

This command finds and deletes log files older than 7 days in /path/to/search.

5/ grep: Search for patterns in files.

grep -r "pattern" /path/to/search/directory

This command recursively searches for pattern in files under /path/to/search/directory.

6/ curl: Transfer data from or to a server.

curl -X POST -d '{"key": "value"}' http://example[dot]com/api/endpoint

This command sends a POST request with JSON data to the specified endpoint.

7/ tar: Manipulate archives.

tar -czvf archive.tar.gz /path/to/directory

This command creates a gzipped tar archive of the specified directory.

8/ ssh: Securely connect to a remote server.

ssh user@hostname "command"

This command executes command on the remote server.

9/ scp: Securely copy files between hosts.

scp /path/to/local/file user@remote:/path/to/destination/

This command copies a file from the local system to a remote system.

10/ top: Display and update sorted information about processes.

top -u username

This command displays a dynamic list of processes owned by a specific user.

11/ tail: Output the last part of files.

tail -f /var/log/syslog

This command continuously displays new lines appended to the syslog file.

12/ tr: Translate or delete characters.

echo "Hello World" | tr '[:lower:]' '[:upper:]'

This command converts lowercase characters to uppercase.

13/ xargs: Build and execute command lines from standard input.

find /path/to/search -name "*.txt" | xargs grep "pattern"

This command searches for pattern in all .txt files under /path/to/search.

14/ cut: Remove sections from each line of files.

cat file.txt | cut -d',' -f1

This command extracts the first field from a CSV file.

15/ jq: Command-line JSON processor.

curl http://example[dot]com/api/endpoint | jq '.key'

This command parses JSON output and extracts the value of key.

16/ nc: Utility for reading from and writing to network connections.

nc -l 1234 > received_file

This command listens on port 1234 and saves incoming data to received file.

17/ awk: Print specific fields or columns.

ls -l | awk '{print $9}'

This command prints the names of files in the current directory.

18/ tee: Read from standard input and write to standard output and files.

echo "Hello World" | tee file.txt

This command writes "Hello World" to file.txt and also displays it in the terminal.

19/ cron: Daemon to execute scheduled commands.

crontab -e

This command opens the user's crontab file for editing.

20/ iptables: Administration tool for IPv4 packet filtering and NAT.

iptables -A INPUT -p tcp --dport 22 -j DROP

This command blocks incoming SSH connections on port 22.

Mastering these advanced Linux command line utilities will greatly enhance your efficiency and effectiveness as a DevOps engineer.