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01: Essential Tools (RHCSA Foundation)

This section covers the fundamental command-line tools required to navigate, manage, and troubleshoot a Red Hat Enterprise Linux system. Proficiency here is mandatory for speed and accuracy during the EX200 exam.

🎯 Exam Objectives Covered

  • Shell Access & Command Syntax: Log in, switch users, and use correct syntax.
  • I/O Redirection: Use >, >>, |, 2>, and &> to manage data flow.
  • Text Analysis: Use grep and Regular Expressions (regex) to filter logs and files.
  • Remote Access: Securely access systems using ssh and key-based auth.
  • Archiving & Compression: Use tar with gzip (z) and bzip2 (j).
  • File Management: mkdir, cp, mv, rm, and creating hard/soft links.
  • Permissions: Standard ugo/rwx permissions and umask.
  • System Documentation: Efficiently using man, info, and /usr/share/doc.

🛠️ Key Command Reference

1. File Management & Links

Task Command
Create Soft Link ln -s /path/to/original linkname
Create Hard Link ln /path/to/original linkname
Recursive Copy cp -rp /source /destination (p preserves permissions)

2. Search & Filter (Grep/Regex)

  • Search for a string (case insensitive): grep -i "error" /var/log/messages
  • Search for lines starting with "root": grep "^root" /etc/passwd
  • Search for lines ending with "nologin": grep "nologin$" /etc/passwd

3. Archive & Compress

  • Create Gzip Archive: tar -cvzf archive.tar.gz /path/to/dir
  • Extract Bzip2 Archive: tar -xvjf archive.tar.bz2 -C /target/dir

4. Permissions (The Basics)

  • Change Ownership: chown user:group filename
  • Numeric Permissions: chmod 755 filename (rwxr-xr-x)
  • Symbolic Permissions: chmod g+w,o-r filename

🚀 Lab Exercises to Practice

  1. The Link Test: Create a file, create both a hard and soft link to it, delete the original file, and see which link still works.
  2. The Grep Challenge: Find all files in /etc that contain the word "network" and save the list to ~/network_files.txt.
  3. The Archive Drill: Archive the /etc/ssh directory into your home folder using tar and verify the contents without extracting.

📝 RHEL 10 Bridge Notes

  • Flatpak: In RHEL 10, this folder will also include flatpak install and repository management commands.
  • Documentation: RHEL 10 places higher emphasis on finding info within the terminal since internet access is prohibited during the exam.