improvements to the ls command - hacktoberfest (#385)

* docs: Add SELinux support details for the `ls` command

* docs: Enhance `ls` command documentation with additional flags and examples

Author: tayeh

ebook/en/content/001-the-ls-command.md

@@ -17,6 +17,42 @@ ls
 ls {Directory_Path}
 ```
 
+3. List all files including hidden ones in long format with human-readable sizes:
+
+```
+ls -lah
+```
+
+4. Sort files by modification time, newest first:
+
+```
+ls -lt
+```
+
+5. List files by size, largest first:
+
+```
+ls -lhS
+```
+
+6. Show only directories in the current path:
+
+```
+ls -d */
+```
+
+7. List all text files with details:
+
+```
+ls -lh *.txt
+```
+
+8. Recursively list all files in subdirectories:
+
+```
+ls -R
+```
+
 ### Syntax:
 
 ```
@@ -44,6 +80,131 @@ In this interactive tutorial, you will learn the different ways to use the `ls`
 |`-d`|`--directory`|Instead of listing the files and directories inside the directory, it shows any information about the directory itself, it can be used with `-l` to show long formatted information|
 |`-F`|`--classify`|Appends an indicator character to the end of each listed name, as an example: `/` character is appended after each directory name listed|
 |`-h`|`--human-readable`|like `-l` but displays file size in human-readable unit not in bytes|
+|`-i`|`--inode`|Display inode number for each file|
+|`-R`|`--recursive`|List subdirectories recursively|
+|`-1`|<center>-</center>|List one file per line|
+|`-c`|<center>-</center>|Sort by change time (when file metadata was last changed)|
+|`-u`|<center>-</center>|Sort by access time (when file was last accessed)|
+|`-X`|<center>-</center>|Sort alphabetically by file extension|
+|<center>-</center>|`--color=auto`|Colorize output to distinguish file types|
+|`-g`|<center>-</center>|Like `-l` but without showing owner|
+|`-o`|<center>-</center>|Like `-l` but without showing group|
+|<center>-</center>|`--group-directories-first`|List directories before files|
+
+
+### File Type Indicators:
+
+When using the `-F` or `--classify` flag, `ls` appends special characters to filenames to indicate their type:
+
+|**Indicator**|**File Type**|**Example**|
+|:---|:---|:---|
+|`/`|Directory|`docs/`|
+|`*`|Executable file|`script.sh*`|
+|`@`|Symbolic link|`link@`|
+|`\|`|FIFO (named pipe)|`pipe\|`|
+|`=`|Socket|`socket=`|
+|No indicator|Regular file|`file.txt`|
+
+**Example:**
+
+```bash
+ls -F
+documents/  script.sh*  link@  data.txt  pipe|  socket=
+```
+
+
+### SELinux Support on Red Hat-Based Systems:
+
+On Red Hat-based distributions (RHEL, CentOS, Fedora, Rocky Linux, AlmaLinux) that use SELinux, the `ls` command provides additional options to display SELinux security context information:
+
+|**Short Flag**   |**Long Flag**   |**Description**   |
+|:---|:---|:---|
+|`-Z`|`--context`|Display SELinux security context for files and directories|
+|`-lZ`|<center>-</center>|Show long format with SELinux security context|
+
+**Example Output:**
+
+```bash
+ls -Z
+unconfined_u:object_r:user_home_t:s0 file.txt
+unconfined_u:object_r:user_home_t:s0 directory
+```
+
+```bash
+ls -lZ
+-rw-rw-r--. 1 user user unconfined_u:object_r:user_home_t:s0 1234 Jan 15 10:30 file.txt
+drwxrwxr-x. 2 user user unconfined_u:object_r:user_home_t:s0 4096 Jan 15 10:25 directory
+```
+
+The SELinux context format is: `user:role:type:level`
+
+**Note:** The `-Z` option is only functional on systems with SELinux enabled. On non-SELinux systems, this option may not be available or will show no additional information.
+
+
+### Understanding Long Format Output:
+
+When using `ls -l`, each line displays detailed information about a file or directory:
+
+```bash
+-rw-r--r-- 1 user group 1234 Jan 15 10:30 file.txt
+```
+
+**Column breakdown:**
+
+1. **File Type and Permissions** (`-rw-r--r--`):
+   - First character: File type (`-` = regular file, `d` = directory, `l` = symlink, `b` = block device, `c` = character device, `p` = pipe, `s` = socket)
+   - Next 9 characters: Permissions in three groups (owner, group, others)
+     - `r` = read, `w` = write, `x` = execute, `-` = no permission
+
+2. **Link Count** (`1`): Number of hard links to the file
+
+3. **Owner** (`user`): Username of the file owner
+
+4. **Group** (`group`): Group name that owns the file
+
+5. **Size** (`1234`): File size in bytes (use `-h` flag for human-readable format like `1.2K`, `3.4M`)
+
+6. **Modification Time** (`Jan 15 10:30`): Date and time the file was last modified
+
+7. **Filename** (`file.txt`): Name of the file or directory
+
+**Example with human-readable sizes:**
+
+```bash
+ls -lh
+drwxr-xr-x 2 user group 4.0K Jan 15 10:25 documents
+-rwxr-xr-x 1 user group 2.3M Jan 14 09:15 script.sh
+-rw-r--r-- 1 user group  15K Jan 16 14:30 data.csv
+```
+
+
+### Using Wildcards and Patterns:
+
+The `ls` command supports wildcards for pattern matching:
+
+|**Wildcard**|**Description**|**Example**|**Matches**|
+|:---|:---|:---|:---|
+|`*`|Matches any number of characters|`ls *.txt`|All files ending with `.txt`|
+|`?`|Matches exactly one character|`ls file?.txt`|`file1.txt`, `file2.txt`, but not `file10.txt`|
+|`[]`|Matches any character within brackets|`ls file[123].txt`|`file1.txt`, `file2.txt`, `file3.txt`|
+|`[!]`|Matches any character NOT in brackets|`ls file[!3].txt`|`file1.txt`, `file2.txt`, but not `file3.txt`|
+|`{}`|Matches any of the comma-separated patterns|`ls *.{jpg,png,gif}`|All image files with these extensions|
+
+**Examples:**
+
+```bash
+# List all PDF and DOCX files
+ls *.{pdf,docx}
+
+# List files starting with 'test' followed by a single digit
+ls test?.log
+
+# List all files starting with uppercase letters
+ls [A-Z]*
+
+# List all hidden configuration files
+ls .config*
+```
 
 
 ### SELinux Support on Red Hat-Based Systems:
@@ -97,3 +258,78 @@ Customizing command behavior in Linux is easy using the `alias` command. To make
 3. **Verification**: Open a new terminal session, and the `ls` command will display files as configured.
 
 
+### Performance Tips:
+
+**1. Avoid recursive listing on large directories:**
+   - The `-R` flag can be slow on directories with many subdirectories and files
+   - Consider using `find` command for more control: `find /path -type f`
+
+**2. Disable color output in scripts:**
+   - Use `--color=never` when piping output or in scripts to improve performance
+   - Example: `ls --color=never | grep pattern`
+
+**3. Limit output for large directories:**
+   - Combine with `head` to see only first few entries: `ls -1 | head -n 20`
+   - Or use `ls -1 | wc -l` to just count files without displaying them
+
+**4. Use specific paths instead of wildcards when possible:**
+   - `ls /var/log/syslog` is faster than `ls /var/log/sys*` when you know the exact filename
+
+
+### Common Use Cases:
+
+**1. Find the largest files in a directory:**
+
+```bash
+ls -lhS | head -n 10
+```
+
+**2. List only directories:**
+
+```bash
+ls -d */
+```
+
+Or with full details:
+
+```bash
+ls -ld */
+```
+
+**3. Count files in a directory:**
+
+```bash
+ls -1 | wc -l
+```
+
+**4. List files modified in the last 24 hours:**
+
+```bash
+ls -lt | head
+```
+
+**5. Show files sorted by extension:**
+
+```bash
+ls -lX
+```
+
+**6. List files with their inode numbers (useful for debugging):**
+
+```bash
+ls -li
+```
+
+**7. Display directory contents one per line (useful for scripting):**
+
+```bash
+ls -1
+```
+
+**8. Combine multiple sort options (size + reverse):**
+
+```bash
+ls -lhSr
+```
+
+