session-16-systemUtilities.md

Session 15: System Utilities

find

Purpose: Locates files in a directory hierarchy based on specified criteria.

Syntax:

find path -options arguments

Common Options:

• -type: Specifies the file type (e.g., f for regular files, d for directories).
• -name: Matches files based on their name.
• -newer: Matches files modified after a given file.

Example:

find . -type f -name "*.txt" -newer file.txt

This finds all regular files named "*.txt" in the current directory or subdirectories that were modified after file.txt.

locate

Purpose: Quickly finds files based on their name.

Syntax:

locate pattern

Note: locate uses a database of file names that is periodically updated using the updatedb command.

Example:

updatedb
locate myfile.txt

time

Purpose: Measures the execution time of a command.

Syntax:

time command

Example:

time ls -l

date

Purpose: Displays the current date and time.

Syntax:

date

timedatectl

Purpose: Provides more detailed information about the system's date and time settings.

Syntax:

timedatectl

sleep

Purpose: Pauses the execution of a script for a specified number of seconds.

Syntax:

sleep seconds

Compression and Decompression

1. tar

Purpose: Creates and extracts tar archives.

Syntax:

tar -cvzf archive.tar.gz files

Options:

• -c, --create: Create a new archive.
• -x: To extract an archive.
• -v: Verbose output.
• -z: Use gzip compression.
• -f: Specify the archive file.
• -r, --apend: Append files to the end of an archive.
• -t, --list: list the contents of an archive

Example:

tar -cvzf backup.tar.gz important_files

2. zip

Purpose: Creates ZIP archives.

Syntax:

zip archive.zip files

Example:

zip backup.zip important_files

3. gzip

Purpose: Compresses and decompresses files using gzip.

Syntax:

gzip -c file.txt > file.txt.gz
gzip -d file.txt.gz

Example:

gzip -c myfile.txt > myfile.txt.gz
gzip -d myfile.txt.gz

4. bzip2

Purpose: Compresses and decompresses files using bzip2.

Syntax:

bzip2 -c file.txt > file.txt.bz2
bzip2 -d file.txt.bz2

Example:

bzip2 -c myfile.txt > myfile.txt.bz2
bzip2 -d myfile.txt.bz2

Note

• zcat and bzcat are equivalent to gzip -dc and bzip2 -dc, respectively.
• zmore and bzmore are similar to more but for compressed files.
• zless and bzless are similar to less but for compressed files.