Bash Commands

Braces Expansion

This is a cool technique to perform multiple operations via a simple modification

$ cp config.json{,.backup}        # copy existing file as config.json.backup
$ mkdir -p project/{a,b,c}/src    # Create multiple directory structures.
    $ tree                            # Validate the directory structures created above
$ echo pre-{a,b,c}-post           # Returns pre-a-post, pre-b-post, pre-c-post
$ echo {1..10}                    # Returns integer sequence 1 to 10
$ echo {a..j}                     # Returns char sequence from a to j

Part of the expansion are few unique commands
$ !!                 # Runs the last command executed. Useful when you forgot to add sudo
$ sudo !!

$ !$                 # Refers to the last argument of the previous command
$ touch script.sh
$ chmod +x !$        # This will already know to replace script.sh here

Pipes

Pipes pass output of one command to the next command

$ uglify -c -m -- index.js | gzip -9 | wc -c

uglify    # npm module installed globally
-c        # compress file
-m        # minify file
-9        # Compress to maximum
-c        # Return byte count instead of word count

Commands

which command        // Returns the location of the binary installed
env                  // Prints out all the environment variables
sudo env             // Prints out all the environment variables for sudo not the current user
command -v ls        // Returns the location of the binary installed. Seems same as `which` command
hostname

tee    - utility copies standard input to standard output, making a copy in zero or more files. Output is unbuffered.

dash               // built-in command interpreter
sh                 // short hand for dash
lsmod              // lists statuses of modules in the Linux Kernel
reboot             // reboots the machine
ls -la /dev        // List all the available devices
ls -la /dev | grep cdrom               // filter on available devices
ls -la /media/cdrom                    // destination directory???
sudo mount <device> <destination>      // Mount a device
sudo mount /dev/cdrom /media/cdrom
id                                     // Displays user and group information
getent group vboxsf                    // Display who all have access to the folder???
sudo usermod -a -G vboxsf <name>       // Provide user access
ls -1 | grep apache
sudoedit sites-available/vboxsf.conf

Apache
======
ports.conf
sudo a2ensite vboxsf
sudo a2dissite 000-default
service apache2 reload

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Last update: March 4, 2023