Working with Files in Linux

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Working with files is an essential part of Linux, and it’s a skill every Linux user must master. In Linux, everything is considered a file: text documents, images, system files, devices, and even directories. Linux provides numerous command-line utilities to create, view, move, or search files. Some of the basic commands for file handling in the Linux terminal include touch for creating files, mv for moving files, cp for copying files, rm for removing files, and ls for listing files and directories.

For example, to create a file named example.txt, you can use the following command:

%%bash
cd /tmp/
mkdir documents
cd documents
touch example.txt

To list the files in the current directory, use the command:

%%bash
cd /tmp/documents
ls

Knowing how to effectively manage and manipulate files in Linux is crucial for administering and running a successful Linux system.

File Permissions

Linux is a multi-user system, and file permissions play a vital role in protecting files from unauthorized access or modification. Every file and directory has associated permissions that determine who can read, write, or execute the file.

  • r (read): Allows reading the file.

  • w (write): Allows modifying the file.

  • x (execute): Allows running the file as a program.

To view file permissions, use:

%%bash
cd /tmp/documents
ls -l

To modify file permissions, use chmod:

%%bash
cd /tmp/documents
touch file.txt
ls -l file.txt
chmod 755 file.txt
ls -l file.txt
chmod +x file.txt
ls -l file.txt
chmod go+x file.txt
ls -l file.txt

This sets the file permissions to rwxr-xr-x, where the owner can read, write, and execute the file, while others can only read and execute it.

Archiving and Compressing

Archiving and compressing files helps manage storage and transfer large amounts of data efficiently. In Linux, commands like tar, gzip, and bzip2 are used for this purpose.

To create an archive of files:

%%bash
cd /tmp/documents
touch file1.txt
tar -cvf archive.tar file.txt file1.txt
ls -l

To compress the archive:

%%bash
cd /tmp/documents
gzip archive.tar
ls -l

The file will now be compressed as archive.tar.gz.

To extract a tar file:

%%bash
cd /tmp/documents
mkdir temp
cd temp
tar -xzvf ../archive.tar.gz
ls -lrt

Copying and Renaming Files

Copying and renaming files are essential operations when managing file systems. The cp command is used to copy files, and mv is used both to move and rename files.

To copy a file:

%%bash
cd /tmp/documents
cp file.txt /tmp
ls /tmp

To rename a file:

%%bash
cd /tmp/documents
mv /tmp/file.txt newname.txt
ls

To move a file to a different directory:

%%bash
cd /tmp/documents
mv newname.txt /tmp
ls /tmp

Links in Linux are shortcuts to files or directories. There are two types of links: soft links (symbolic links) and hard links.

  • Soft Link (Symbolic Link): A pointer to a file or directory. Removing the original file breaks the link.

Example:

%%bash
cd /tmp/documents
rm -f softlink.txt
ln -s file.txt softlink.txt

  • Hard Link: A copy of the file’s inode, meaning it references the same data as the original file. Deleting the original file does not break the link.

Example:

%%bash
cd /tmp/documents
rm -f newlink.txt
ln file.txt newlink.txt

Hard links can only be created for files on the same filesystem.

Summary

File management in Linux is a fundamental task that includes working with file permissions, compressing files, copying/renaming files, and creating links. These skills ensure efficient handling of data and system administration tasks.