LPIC-1 Tutorial: Finding System Files and Placing Them in the Correct Location #

Introduction #

Understanding the Filesystem Hierarchy Standard (FHS) is crucial for effective Linux system administration. The FHS defines the directory structure and directory contents in Unix-like operating systems. This tutorial will cover the FHS, demonstrate how to find files and commands on a Linux system, and explain the purpose of important files and directories.

Filesystem Hierarchy Standard (FHS) #

The FHS is a standardized structure for file and directory placement in Unix-like systems. Here are some key directories and their purposes:

• /: The root directory, the top-level directory of the filesystem.
• /bin: Essential command binaries needed for single-user mode and to bring up the system.
• /sbin: System binaries, essential for system administration.
• /etc: Host-specific system configuration files.
• /usr: Secondary hierarchy for read-only user data; contains the majority of user utilities and applications.
• /var: Variable data, such as logs, mail, and spool files.
• /home: User home directories.
• /tmp: Temporary files.

Finding Files and Commands #

find #

The find command searches for files and directories in a directory hierarchy.

Examples:

• Find all .log files in /var/log:

  find /var/log -name "*.log"
  

• Find all files larger than 100MB:

  find / -size +100M
  

locate #

The locate command searches a database of filenames. It’s faster than find but may not have the most recent file changes unless the database is updated.

Examples:

• Locate files named passwd:

  locate passwd
  

• Update the locate database (requires superuser privileges):

  sudo updatedb
  

updatedb #

updatedb updates the database used by locate.

Configuration file: /etc/updatedb.conf

Example:

• Update the locate database:

  sudo updatedb
  

whereis #

The whereis command locates the binary, source, and manual page files for a command.

Examples:

• Locate ls command files:

  whereis ls
  

which #

The which command shows the full path of shell commands.

Examples:

• Find the path of grep:

  which grep
  

type #

The type command displays information about a command type.

Examples:

• Find the type of ls:

  type ls
  

Location and Purpose of Important Files and Directories #

/etc #

The /etc directory contains host-specific system configuration files.

Examples:

• /etc/passwd: User account information.
• /etc/fstab: Filesystem mount table.
• /etc/hosts: Static table lookup for hostnames.

/var #

The /var directory holds variable data files, such as logs and spools.

Examples:

• /var/log: Log files.
• /var/spool: Spool directories for tasks like printing and mail.

/usr #

The /usr directory is for user utilities and applications.

Examples:

• /usr/bin: Non-essential command binaries.
• /usr/lib: Libraries for /usr/bin and /usr/sbin binaries.

Real-World Examples #

Ubuntu/Debian vs. Enterprise Linux (RHEL/CentOS) #

While the basics of the commands remain the same across different Linux distributions, there can be differences in the paths or the way certain commands are used. Here are some specific examples:

Updating the locate database:

• Ubuntu/Debian:

  sudo updatedb
  

• RHEL/CentOS:

  sudo /usr/bin/updatedb
  

Finding the crontab command:

• Ubuntu/Debian:

  which crontab
  # Output: /usr/bin/crontab
  

• RHEL/CentOS:

  which crontab
  # Output: /usr/bin/crontab
  

Finding configuration files:

• Ubuntu/Debian:

  find /etc -name "*.conf"
  

• RHEL/CentOS:

  find /etc -name "*.conf"
  

Despite these similarities, be aware of distribution-specific tools and configurations.

Conclusion #

Understanding the FHS and being able to find and place files correctly are fundamental skills for a Linux system administrator. The commands find, locate, updatedb, whereis, which, and type are essential tools for navigating and managing the filesystem. This tutorial provided an overview of these tools and their usage, along with examples highlighting any differences between Ubuntu/Debian and Enterprise Linux systems.