Update README.md

commands/README.md

@@ -1,58 +1,75 @@
 # Bash commands
-
-  - <b> List Operations: </b>
-    - `ls` - shows list of files and directories.
-    - `ls -l` - shows users, permissions, group owners, etc.
-    - `ls -a` - also shows hidden files.
-    - `ls -al` - combination of ls -a and ls -l
-    - `ls -R` - also shows files in sub directories. </br>
-
-  - <b> Directory Operations: </b>
-    - `open .` - opens current directory in files
-    - `pwd` - displays the present working directory
-    - `mkdir <dir-name>` - creates a new directory.
-    - `mkdir <dir1-name> <dir2-name>` - creates a new directory in existing directory.
-    - `mkdir -p <dir1-name> <dir2-name> <dir3-name>` - creates a new directory in between existing directories.
-    - `cd folder-name`
-    - `cd` - go to home directory
-    - `cd ..` - go back </br>
-      . means current directory and .. means previous directory
-    - `cd ../folder-name` --> in the previous directory there is another directory.
-    - `rm -r folder-name` - removes a folder permanently.
-    - `rmdir <dir-name>` - to remove an empty directory.
-      - `rmdir -rf <dir-name>` - removes a non-empty directory.
-    - `find .` - find in current directory.
-    - `find ..` - find in previous directory.
-    - `find <folder-name>` - find in folder.
-    - `find . -type d` - displays files in current directory of type directory.
-    - `find . -type f` - displays files in current directory of type file.
-    - `find . -type f -name <file-name>`
+  - <b> Basic Operations:</b>
+      - Locating Applications:
+          - `which [command]` - Locates and displays source of file
+          - `whereis [command]` - Locates and displays source of file. It also looks for packages in a broader range of system directories.
+      - Accessing Directories:
+          - `pwd` - Displays the present working directory.
+          - `cd` - Go to home directory
+              - `cd ..` - Go back </br>
+              . means current directory and .. means previous directory
+              - `cd ../folder-name` --> In the previous directory there is another directory.
+              - `cd -` - Change to previous working directory; - (minus)
+      - Exploring the File System:
+          - `cd /` - Changes your current directory to the root (/) directory (or path you supply).
+          - `ls` - List the contents of the present working directory.
+              - `ls -a` - List all files, including hidden files and directories (those whose name start with . )
+              - `ls -l` - Shows users, permissions, group owners, etc.
+              - `ls -li /path/to/directory` -  Used to list files and directories in a directory. The -l option provides a long listing format, and the -i option displays the inode number of each file.
+              - `ls -l *pattern*` - Used to list all files and directories in the current directory that match the specified pattern.
+              - `ls -al` - Combination of ls -a and ls -l
+              - `ls -R` - Also shows files in sub directories. </br>
+          - `tree` - Displays a tree view of the filesystem.
+              - `tree -d` - Displays directories only.
+      - Hard and Soft Links:
+          - `ln <source> <destination>` - Used to create hard links.
+          - `ln -s <source> <destination>` - Used to create soft(symbolic) links.
+
+      - Navigating the directory history:
+          - `pushd <directory>` - Used to change the current directory and also save the current directory onto the directory stack.
+          - `popd <directory>` - Used to remove the top directory from the directory stack and change the current directory to the one that was removed from the stack.
+          - `dirs` - Displays the directories in the directory stack in reverse order, with the most recent directory listed first.   
+
+  - <b> File Operations: </b>
+    - `cat` - Used for viewing files that are not very long; it does not provide any scroll-back.
+        - `cat -n` - Also displays the line numbers.
+    - `wc <file>` - Prints the number of lines, words and characters in file.
+    - `tac`- Used to look at a file backwards, starting with the last line.
+    - `less` - Used to view larger files because it is a paging program. It pauses at each screen full of text, provides scroll-back capabilities, and lets you search and navigate within the file.
+
+     *NOTE: Use / to search for a pattern in the forward direction and ? for a pattern in the backward direction. An older program named more is still used, but has fewer capabilities: "less is more".*
+    - `head <file-name>` - Displays the first 10 lines of file.
+        - `head -4 <file-name>` - Displays the first 4 lines of file.
+    - `tail <file-name>` - Displays the last 10 lines of file by default.
+        - `tail -2 <file-name>` - Displays last 2 lines of file by default.
+    - `touch <file-name>` - Creates a new file.
+    - `touch <folder-name>/<file-name>` - Creates a file in a folder.
+    - `echo > <file-name>` - Creates a new file 
+    - `mv <file1-name> <file2-name>` - Renames file1-name to file2-name.
+    - `mv <file-name> <dir-name>` - Moves file into directory.
+    - `mv <file-name ../<newFile-name>` - Move and create a new file in previous directory.
+    - `rm <file-name>` - Removes a file permanently. 
+      - `rm -f <file-name>` - Forces deletion of file in certain scenarios when the file is unable to delete. For example, if the file is open, etc.
+      - `rm -i <file-name>` - Used to remove (delete) files and directories from the file system. The system will display a prompt for each item, asking you to confirm whether you want to delete it. You can then respond with "y" (yes) or "n" (no).
+      - `rm -rf <file-name>` - Forcefully remove a directory recursively.
+      - `locate <file-name>` - locates the file.
+      - `locate ".txt"` - displays all the files that end with an extension of .txt
+      - `find . -type d` - displays files in current directory of type directory.
+      - `find . -type f` - displays files in current directory of type file.
+      - `find . -type f -name <file-name>`
         - `-type f -name f*` - shows files starting with f.
         - `-type f -name "*.txt"` - shows files of type .txt
         - `-type f -iname "*.txt"` - shows files of type .txt that are not case sensitive.
         - `-type f -mmin -20` - displays files that were modified less than 20 min ago.
         - `-type f -mmin +20` - displays files that were modified more than 20 min ago.
         - `-type f -maxdepth 2` - 
-    - `find . -size +1k` - shows files/folders with size greater than 1kb.
-    - `find . -empty` - shows files that are empty.
-
-
-  - <b> File Operations: </b>
-    - `touch <file-name>` - creates a new file.
-    - `touch <folder-name>/<file-name>` - creates a file in a folder.
-    - `cp <file1-name> <file2-name>` - copy file1 contents in file2.
-    - `mv <file1-name> <file2-name>` - renames file1-name to file2-name.
-    - `mv <file-name> <dir-name>` - moves file into directory.
-    - `mv <file-name ../<newFile-name>` - move and create a new file in previous directory.
-    - `rm <file-name>` - removes a file permanently. 
-      - `rm -f <file-name>` - forces deletion of file in certain scenarios when the file is unable to delete. For example, if the file is open, etc.
-    - `head <file-name>` - displays the first 10 lines of file.
-    - `head -n 4 <file-name>` - displays the first 4 lines of file.
-    - `tail <file-name>` - displays the last 10 lines of file.
-    - `tail -n 2 <file-name>` - displays last 2 lines of file.
+      - `find . -size +1k` - shows files/folders with size greater than 1kb.
+      - `find . -empty` - shows files that are empty.
+
+      -  - `cp <file1-name> <file2-name>` - copy file1 contents in file2.
+
     - `diff <file1-name> <file2-name>` - compares the contents of two file line by line and outputs the lines that do not match.
-    - `locate <file-name>` - locates the file.
-    - `locate ".txt"` - displays all the files that end with an extension of .txt
+
     - `sort <file-name>` - sorts alphabetically.
         - `-r` - sorts in reverse order
         - `-f` - case insensitive sorting
@@ -62,8 +79,9 @@
     - `join <file1-name> <file2-name>` - combines lines from two files based on a common field or key. 
     - Zipping files: `zip <zip-file-name> <file1-name> <file2-name>`
     - Unzipping files: `unzip <file-name>`
-    - `cut -c 1-2 <file-name>` - shows first 2 columns of file.   
-    - `whereis` - locates and displays source of file.
+    - `cut -c 1-2 <file-name>` - shows first 2 columns of file.
+    - `which [command]` - locates and displays source of file 
+    - `whereis [command]` - locates and displays source of file. It also looks for packages in a broader range of system directories.
     - `file <file/directory-name>` - To find the type of files/directories.
 
     - `cat <file-name>` - displays contents of file.
@@ -79,10 +97,46 @@
     - `sed 's/pattern/replacement/' filename` -  searches for pattern in  file and replaces them with the given replacement text.
     - `wc <file>` - prints the number of lines, words and characters in file.
       - `-l` - prints just the number of lines.
+
+  - <b> Directory Operations: </b>
+    - `open .` - opens current directory in files
+    - `pwd` - displays the present working directory
+    - `mkdir <dir-name>` - creates a new directory.
+    - `mkdir <dir1-name> <dir2-name>` - creates a new directory in existing directory.
+    - `mkdir -p <dir1-name> <dir2-name> <dir3-name>` - creates a new directory in between existing directories.
+    - `cd folder-name`
+    - `cd` - go to home directory
+    - `cd ..` - go back </br>
+      . means current directory and .. means previous directory
+    - `cd ../folder-name` --> in the previous directory there is another directory.
+    - `rm -r folder-name` - removes a folder permanently.
+    - `rmdir <dir-name>` - to remove an empty directory.
+      - `rmdir -rf <dir-name>` - removes a non-empty directory.
+    - `find .` - find in current directory.
+    - `find ..` - find in previous directory.
+    - `find <folder-name>` - find in folder.   
 
   - <b> Environmental Variables: </b>
     - `env` - displays environmental variables
-
+
+  - <b> Processes: </b>
+    - `ps` - Displays information about processes currently running on the system.
+        - `ps aux` - Shows a detailed list of all running processes.
+        - `ps -e` - Lists all processes.
+        - `ps -ef` - Provides a full listing with additional details.
+        - `ps -eLf` - Displays one line of information for every thread.
+    - `pstree` - Displays the processes running on the system in the form of a tree diagram showing the relationship between a process and 
+                 its parent process and any other processes that it created.
+    - `top` - Provides an interactive real-time view of system processes.
+    - `htop` - Enhanced version with a more user-friendly interface and additional features.
+    - `pidstat` - Reports statistics for processes, including CPU, memory, and I/O usage.
+    - `vmstat` - Provides information about system-wide virtual memory statistics and can offer insights into process behavior.
+    - `iotop` - Monitors I/O usage by processes and helps identify processes causing high I/O loads.
+    - `w` - Displays information about currently logged-in users, their activities, and system load.
+    - `top` - Provides a dynamic real-time view of system processes and resource usage. provides a dynamic real-time view of system processes 
+              and resource usage. 
+    - `uptime` - Provides a summary of system uptime and load averages.
+
   - <b> Text Editors: </b>
     - `nano <file>` - start the editor and edit file.
     - `gedit <file>` - start the text editor and edit file.
@@ -114,8 +168,6 @@
       - `getent group <user-name>` - to check user exists or not
       - `lsof` - shows all open files.
           - `lsof -u <user-name>` - shows open files for particular user.
-      - `ps aux` - shows processess running.
-
 
   - <b> Permissions:<br> </b>
     There are three types of permissions: **read, write and execute** and there are three types of owners: **user, group and others.**
@@ -165,7 +217,29 @@
     - `nslookup <url/IP address>` - to check IP address for particular domain.
     - `netstat` - shows all active ports 
     - `telnet`
-
+
+  - <b> Finding Documentation: </b>
+    - `man command_name` - To view the manual page of a specific command.
+        - `man -f <command_name>` - To list all pages on the topic. Generates the same result as typing `whatis`.
+        - `man -k <command_name>` - To list all pages that discuss a specific topic (even if the specified subject is not present in the                 name). Generates the same result as typing `apropos`.
+        - `man -a <command_name>` -  Used to display the manual pages for a specified command from all available manual page sections.
+        - `info <topic name>` - To view help for a particular topic. The system then searches for the topic in all available info files.
+        - `<command_name> --help` - Help provides basic information about shell commands.
+
+  - <b> Basic Packaging Commands(deb): </b>
+    - `dpkg --install foo.deb` - Install package.
+    - `apt install foo` - Install package, dependencies.
+    - `dpkg --remove foo.deb` - Remove package.
+    - `apt autoremove foo` - Remove package, dependencies.
+    - `dpkg --install foo.deb` - Update package.
+    - `apt install foo` - Update package, dependencies.
+    - `apt dist-upgrade` - Update entire system.
+    - `dpkg --list` - Show all installed packages.
+    - `dpkg --listfiles foo` - Get information on package.
+    - `dnf list "foo"	apt-cache search foo` - Show packages named foo.
+    - `apt-cache dumpavail foo` - Show all available packages.
+    - `dpkg --search file` - What package is file part of?
+
   - <b> Basic shortcuts: </b>
       - `CTRL-L` - Clears the screen
       - `CTRL-D` - Exits the current shell
@@ -186,13 +260,26 @@
         Example: `git init;git add .;git commit -m "message";git push`
       - `!!(bang bang)` - executes previous command. 
 
-  - <b> Operators: </b>
+  - <b> Operators</b>
+      - I/O Redirection:
+          - `>` - Redirects standard output to a file, overwriting the file if it already exists.
+          - `>>` - Redirects standard output to a file, appending the output to the file if it already exists.
+          - `<` - Redirects standard input from a file.
+          - `2>` - Redirects standard error to a file.
+          - `2>>` - Redirects standard error to a file, appending to the file if it already exists.
+          - `&>` - Redirects both standard output and standard error to a file.
+          - `|` - Redirects the output of one command as input to another command (pipeline).
+
     - `&` - it will create a process in the background so that other commands can be running. We can check the background process using `ps` command and kill it if needed. Example: `ping google.com & facebook.com`
     - `&&` - The command that is succeeding this operator will only execute when the previous one is finish executing. Example: `echo "first" && "second"`
     - `||` - The command that is after the OR operator will only execute if the execution of previous command fails. Example: `echo "first" || echo "second"`
     - `!` - can be use to delete all the files except one particular file.
       Example: `rm -rf !(<file-name>)`
-    - `>>` - use to append contents. example: `"hey" >> <file-name>` file will contain hey.
-    - `>` - use to overwrite.
     - `\` - used to split long commands and execute them as single command.
     - `{}` - combination operator use to group commands. </br>
+
+  - <b> Wildcards </b>
+    - `?` - Matches any single character.
+    -  `*` - Matches any string of characters.
+    - `[set]` - Matches any character in the set of characters, for example [adf] will match any occurrence of a, d, or f.
+    - `[!set]` - Matches any character not in the set of characters.