Top 10 Essential Bash Commands for Devs

10 must-know bash commands, essential for any developer looking to harness the full potential of their software environment.

1. grep - Text Pattern Search

grep is used for searching text patterns within files. It's extremely useful for locating specific strings of text.

• Basic: Search for "error" in filename.log:

  grep 'error' filename.log

• Advanced: Use regular expressions to find complex patterns. For instance, searching for words starting with 'error' followed by a digit:

  grep -E 'error[0-9]' filename.log

2. find - Find Files

find helps locate files and directories based on criteria like name, size, or modification date.

• Basic: Locate .txt files modified in the last 7 days:

  find . -name "*.txt" -mtime -7

• Advanced: Combine with exec to perform actions, like deleting all .tmp files:

  find . -name "*.tmp" -exec rm {} \;

3. tar - File Compression and Extraction

tar is essential for creating and extracting compressed archive files, commonly used for backups and file transfers.

• Basic: Create a tar.gz archive of a directory:

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

• Advanced: Extract specific files from an archive:

  tar -xzvf archive.tar.gz --include="specific_file"

4. awk - Text Processing

awk is a powerful text processing tool, ideal for manipulating data and generating reports.

• Basic: Print the first column from filename.txt:

  awk '{print $1}' filename.txt

• Advanced: Sum the values of a column:

  awk '{sum += $1} END {print sum}' filename.txt

5. sed - Stream Editor

sed allows developers to edit text in a scriptable way, useful for modifying files programmatically.

• Basic: Replace "oldtext" with "newtext" in filename.txt:

  sed 's/oldtext/newtext/' filename.txt

• Advanced: Delete lines matching a pattern:

  sed '/pattern_to_delete/d' filename.txt

6. wget - Download Files

wget enables file downloads from the internet, supporting various protocols like HTTP, HTTPS, and FTP.

• Basic: Download a file from the web:

  wget http://example.com/file.zip

• Advanced: Download a website for offline viewing:

  wget --mirror --convert-links --adjust-extension --page-requisites --no-parent http://example.com

7. chmod - Change File Permissions

chmod changes the file access permissions, crucial for managing the security of files.

• Basic: Change a file's permissions to read and execute only:

  chmod 500 script.sh

• Advanced: Set sticky bit on a directory to maintain user ownership:

  chmod +t /path/to/directory

Change a file's permissions to read and execute only.

chmod 500 script.sh

8. crontab - Schedule Tasks

crontab is used for scheduling tasks to run at specific times, automating routine background jobs.

• Basic: Edit the crontab to add a new scheduled task:

  crontab -e

• Advanced: Schedule a script to run at 5 PM every Friday:

  0 17 * * 5 /path/to/script.sh

9. ssh - Secure Shell Access

ssh provides secure remote access to other computers or servers over an unsecured network.

• Basic: Connect to a remote server:

  ssh username@remote-server.com

• Advanced: Use SSH tunneling for secure browsing:

  ssh -D 8080 -C -N username@remote-server.com

10. tail -f - Monitor File Changes

tail -f allows users to view the end of a file in real-time, helpful for monitoring log files.

• Basic: Follow the updates to a log file in real time:

  tail -f /var/log/syslog

• Advanced: Use with grep to filter logs:

  tail -f /var/log/syslog | grep error