BashCheatSheet

1. soft link
2. Shorcuts to quickly move the cursor around the current line
3. The Difference Between Soft and Hard Links
4. Symbolic (soft) links
5. Save your scripts on...
6. How to use sed to replace strings in macos
7. Create an hyperlink command line

1. soft link

ln -s /pathDirectorySource /PathDirectoryWhereYouWantTheLink

2. Shorcuts to quickly move the cursor around the current line

Enable Meta key. Open Terminal > Preferences > Settings > Keyboard, and enable Use Option as meta key.

• ctrl-A: Go to beginning of the line.
• ctrl-E: Go to the end of the line.

enable Metadata Key, then you can use:

• alt-f: Go forward one word
• alt-b: Go backwards one word -> Very useful

3. The Difference Between Soft and Hard Links

# Hard links

• Only link to a file not a directory
• Can not reference a file on a different disk/volume
• Links will reference a file even if it is moved
• Links reference inode/physical locations on the disk

4. Symbolic (soft) links

• Can link to directories
• Can reference a file/folder on a different hard disk/volume
• Links remain if the original file is deleted
• Links will NOT reference the file anymore if it is moved
• Links reference abstract filenames/directories and NOT physical locations. They are given their own inode

Example 1:

$ ln -s /Users/carlossantiagocruz/Documents/BASH-PROGRAMMING/DICT-EN-ES/trad3.sh /usr/local/bin/trad3

Example 2:

ln -s /Users/carlossantiagocruz/Documents/BASH-PROGRAMMING/MOVER-PDF-2-DIRECTORIO/mover-pdf2directorio.sh /usr/local/bin/mover-pdf2directorio1.0

5. Save your scripts on...

Create a bin directory on your home directory

mkdir bin

12. Create an hyperlink command line

Using echo

echo -e '\e]8;;http://example.com\aThis is a hyperlink\e]8;;\a' 

Using printf

printf '\e]8;;http://example.com\e\\This is a link\e]8;;\e\\\n'

Redirect Output and Errors to /dev/null

The following files are used by Unix process.

ls -l /dev/{stdout,stdin,stderr}

COnsole output:

lr-xr-xr-x  1 root  wheel  0 Nov 26 16:33 /dev/stdout -> fd/1
lr-xr-xr-x  1 root  wheel  0 Nov 26 16:33 /dev/stdin -> fd/0
lr-xr-xr-x  1 root  wheel  0 Nov 26 16:33 /dev/stderr -> fd/2

1. /dev/stdin ( 0 ) – Standard Input (usually keyboard or file). When a command opens /dev/stdin, it can read input from the user.
2. /dev/stdout ( 1 ) – Standard Output (usually screen). When a command writes to /dev/stdout, its output is displayed on the screen.
3. /dev/stderr ( 2 ) – Standard Error (usually screen). When a program or command writes to /dev/stderr, its error messages are displayed on the screen.

What is a /dev/null file in Unix?

/dev/null is a special file in Unix/Linux systems that acts as a "black hole" or "data sink". Here are its key characteristics:

Purpose:

• Discards any data written to it
• Always appears empty when read
• Never stores any data

Discard standard output

command > /dev/null

Discard error output

command 2> /dev/null

Discard both outputs

command > /dev/null 2>&1