feat: Add install command to chapter 4 "advanced" command (#1630)

fix: some linter warning in the chapter and disable linter for md033

docs/books/admin_guide/04-advanced-commands.md

@@ -1,6 +1,7 @@
 ---
-title: Advanced Linux Commands
+title: Advanced Commands for Linux users
 ---
+<!-- markdownlint-disable MD033 -->
 
 # Advanced Commands for Linux users
 
@@ -10,12 +11,12 @@ Advanced commands provide greater customization and controls in more specialized
 
 **Objectives**: In this chapter, future Linux administrators will learn:
 
-:heavy_check_mark: some useful commands not covered in the previous chapter.   
+:heavy_check_mark: some useful commands not covered in the previous chapter.
 :heavy_check_mark: some advanced commands.
 
 :checkered_flag: **user commands**, **Linux**
 
-**Knowledge**: :star:   
+**Knowledge**: :star:
 **Complexity**: :star: :star: :star:
 
 **Reading time**: 20 minutes
@@ -28,7 +29,7 @@ The `uniq` command is a very powerful command, used with the `sort` command, esp
 
 To illustrate how the `uniq` command works, let's use a `firstnames.txt` file containing a list of first names:
 
-```
+```text
 antoine
 xavier
 steven
@@ -45,7 +46,7 @@ steven
 
 With no argument, the `uniq` command will not display identical lines that follow each other in the `firstnames.txt` file:
 
-```
+```bash
 $ sort firstnames.txt | uniq
 antoine
 patrick
@@ -55,14 +56,14 @@ xavier
 
 To display only the rows that appear only once, use the `-u` option:
 
-```
+```bash
 $ sort firstnames.txt | uniq -u
 patrick
 ```
 
 Conversely, to display only the lines that appear at least twice in the file, use the `-d` option:
 
-```
+```bash
 $ sort firstnames.txt | uniq -d
 antoine
 steven
@@ -71,7 +72,7 @@ xavier
 
 To simply delete lines that appear only once, use the `-D` option:
 
-```
+```bash
 $ sort firstnames.txt | uniq -D
 antoine
 antoine
@@ -84,15 +85,15 @@ xavier
 
 Finally, to count the number of occurrences of each line, use the `-c` option:
 
-```
+```bash
 $ sort firstnames.txt | uniq -c
       3 antoine
       1 patrick
       2 steven
       2 xavier
 ```
 
-```
+```bash
 $ sort firstnames.txt | uniq -cd
       3 antoine
       2 steven
@@ -107,7 +108,7 @@ The `xargs` command reads whitespace or linefeed delimited arguments from standa
 
 A first and simplest example would be the following:
 
-```
+```bash
 $ xargs
 use
 of
@@ -118,7 +119,7 @@ use of xargs
 
 The `xargs` command waits for an input from the standard **stdin** input. Three lines are entered. The end of the user input is specified to `xargs` by the keystroke sequence <kbd>CTRL</kbd>+<kbd>D</kbd>. `xargs` then executes the default command `echo` followed by the three arguments corresponding to the user input, namely:
 
-```
+```bash
 $ echo "use" "of" "xargs"
 use of xargs
 ```
@@ -127,7 +128,7 @@ It is possible to specify a command to be run by `xargs`.
 
 In the following example, `xargs` will run the command `ls -ld` on the set of folders specified in the standard input:
 
-```
+```bash
 $ xargs ls -ld
 /home
 /tmp
@@ -142,7 +143,7 @@ In practice, the `xargs` command executed the `ls -ld /home /tmp /root` command.
 
 What happens if the command to be executed does not accept multiple arguments, such as with the `find` command?
 
-```
+```bash
 $ xargs find /var/log -name
 *.old
 *.log
@@ -151,14 +152,14 @@ find: paths must precede expression: *.log
 
 The `xargs` command attempted to execute the `find` command with multiple arguments behind the `-name` option, which caused `find` to generate an error:
 
-```
+```bash
 $ find /var/log -name "*.old" "*.log"
 find: paths must precede expression: *.log
 ```
 
 In this case, the `xargs` command must be forced to execute the `find` command several times (once per line entered as standard input). The `-L` option followed by an **integer** allows you to specify the maximum number of entries to be processed with the command at one time:
 
-```
+```bash
 $ xargs -L 1 find /var/log -name
 *.old
 /var/log/dmesg.old
@@ -177,7 +178,7 @@ $ xargs -L 1 find /var/log -name
 
 To specify both arguments on the same line, use the `-n 1` option:
 
-```
+```bash
 $ xargs -n 1 find /var/log -name
 *.old *.log
 /var/log/dmesg.old
@@ -195,7 +196,7 @@ $ xargs -n 1 find /var/log -name
 
 Case study of a backup with a `tar` based on a search:
 
-```
+```bash
 $ find /var/log/ -name "*.log" -mtime -1 | xargs tar cvfP /root/log.tar
 $ tar tvfP /root/log.tar
 -rw-r--r-- root/root      1720 2017-04-05 15:43 /var/log/boot.log
@@ -206,8 +207,8 @@ The special feature of the `xargs` command is that it places the input argument
 
 Using the example of the `cp` command, to copy a list of files in a directory, this list of files will be added at the end of the command... but what the `cp` command expects at the end of the command is the destination. To do this,  use the `-I` option to put the input arguments somewhere else than at the end of the line.
 
-```
-$ find /var/log -type f -name "*.log" | xargs -I % cp % /root/backup
+```bash
+find /var/log -type f -name "*.log" | xargs -I % cp % /root/backup
 ```
 
 The `-I` option allows you to specify a character (the `%` character in the above example) where the input files to `xargs` will be placed.
@@ -229,13 +230,14 @@ The `repoquery` command is used to query the packages in the repository.
 Examples of use:
 
   * Display the dependencies of a package (it can be a software package that has been installed or not installed), equivalent to `dnf deplist <package-name>`
-    ```
+
+    ```bash
     repoquery --requires <package-name>
     ```
-    
+
   * Display the files provided by an installed package (does not work for packages that are not installed), equivalent to `rpm -ql <package-name>`
 
-    ```
+    ```bash
     $ repoquery -l yum-utils
     /etc/bash_completion.d
     /etc/bash_completion.d/yum-utils.bash
@@ -273,7 +275,7 @@ The `yumdownloader` command downloads RPM packages from the repositories.  Equiv
 
 Example: `yumdownloader` will download the _samba_ rpm package and all its dependencies:
 
-```
+```bash
 $ yumdownloader --destdir /var/tmp --resolve samba
 or
 $ dnf download --downloadonly --downloaddir /var/tmp  --resolve  samba
@@ -294,7 +296,7 @@ The `psmisc` package contains utilities for managing system processes:
 
 Examples:
 
-```
+```bash
 $ pstree
 systemd─┬─NetworkManager───2*[{NetworkManager}]
         ├─agetty
@@ -314,13 +316,13 @@ systemd─┬─NetworkManager───2*[{NetworkManager}]
         └─tuned───4*[{tuned}]
 ```
 
-```
+```bash
 # killall httpd
 ```
 
 Kill processes (option `-k`) that access the `/etc/httpd/conf/httpd.conf` file:
 
-```
+```bash
 # fuser -k /etc/httpd/conf/httpd.conf
 ```
 
@@ -338,13 +340,13 @@ Examples:
 
 * Display the end of the `/etc/passwd` file every 5 seconds:
 
-```
-$ watch -n 5 tail -n 3 /etc/passwd
+```bash
+watch -n 5 tail -n 3 /etc/passwd
 ```
 
 Result:
 
-```
+```bash
 Every 5.0s: tail -n 3 /etc/passwd                                                                                                                                rockstar.rockylinux.lan: Thu Jul  1 15:43:59 2021
 
 sssd:x:996:993:User for sssd:/:/sbin/nologin
@@ -354,12 +356,86 @@ sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
 
 * Monitoring the number of files in a folder:
 
-```
-$ watch -n 1 'ls -l | wc -l'
+```bash
+watch -n 1 'ls -l | wc -l'
 ```
 
 * Display a clock:
 
+```bash
+watch -t -n 1 date
+```
+
+## `install` command
+
+Contrary to what its name might suggest, the `install` command is not used to install new packages.
+
+This command combines file copying (`cp`) and directory creation (`mkdir`), with rights management (`chmod`, `chown`) and other useful functionalities (like backups).
+
+```bash
+install source dest  
+install -t directory source [...]
+install -d directory
+```
+
+Options:
+
+| Options | Remarks                                                      |
+| ------- | ------------------------------------------------------------ |
+| `-b` or `--backup[=suffix]` | create a backup of destination file.     |
+| `-d`    | treat arguments as directory names.                          |
+| `-D`    | create all leading components before copying SOURCE to DEST. |
+| `-g` and `-o`    | set ownership.                                      |
+| `-m`    | set permissions.                                             |
+| `-p`    | preserve the timestamps of sources files.                    |
+| `-t`    | copy all source arguments to directory.                      |
+
+!!! NOTE
+    There are options for managing the SELinux context (see the manual page).
+
+Examples:
+
+Create a directory with the `-d` option:
+
+```bash
+install -d ~/samples
+```
+
+Copy a file from a source location to a directory:
+
+```bash
+install src/sample.txt ~/samples/
+```
+
+These two orders could have been carried out with a single command:
+
+```bash
+$ install -v -D -t ~/samples/ src/sample.txt
+install: creating directory '~/samples'
+'src/sample.txt' -> '~/samples/sample.txt'
+```
+
+This command already saves time, now let's combine it with owner, owner group and rights management:
+
+```bash
+sudo install -v -o rocky -g users -m 644 -D -t ~/samples/ src/sample.txt
 ```
-$ watch -t -n 1 date
+
+ !!! NOTE
+     `sudo` is required in this case to make property changes.
+
+You can also create a backup of existing files thanks to the `-b` option:
+
+```bash
+$ install -v -b -D -t ~/samples/ src/sample.txt
+'src/sample.txt' -> '~/samples/sample.txt' (archive: '~/samples/sample.txt~')
+```
+
+As you can see, the `install` command creates a backup file with a `~` tilde appended to the original file name.
+
+The suffix can be specified thanks to the `-S` option:
+
+```bash
+$ install -v -b -S ".bak" -D -t ~/samples/ src/sample.txt
+'src/sample.txt' -> '~/samples/sample.txt' (archive: '~/samples/sample.txt.bak')
 ```