How to use vi style in Bash

If you are vi fans, probably you want to have vi command style in bash shell.

Simply add the following command in your ~/.profile_bash file:

set -o vi

That's all :)

How to get yesterday time

Sometimes, we need to create a simple script in linux which involves retrieving system time several days/hours/minutes ago.

Belows are example use of date command:

To get yesterday time:

$ date --date="1 days ago"

or

$ date --date="-1 days"

To get one month ago:

$ date --date="1 months ago"

or

$ date --date="-1 months"

To get one hour ago:

$ date --date="1 hours ago"

or

$ date --date="-1 hours"

To get one minutes in the future:

$ date --date="+1 minutes"

To get one seconds in the future:

$ date --date="+1 seconds"

We can also combine it, example to get one month and two hours ago:

$ date --date="1 month 2 hours ago"

or

$ date --date="-1 month -2 hours"

There are many other ways to express the particular time.

That's all :)

Bash keyboard shortcut

Below is list of keyboard shortcut for bash shell.

Why we need keyboard shortcut? The short answer is: to save time!
Especially, when we are accessing bash remotely (eg: by ssh) and the network access pretty slow, we will need a keyboard shortcut such as deleting the entire command line, moving to the beginning of the command, etc to save a lot of time.

Below are some of keyboard shortcuts for bash. Maybe in certain conditions it does not work properly.

• ALT + b : move the cursor backward one word.


• ALT + f : move the cursor forward one word.


• ALT + d : cut one word after the cursor.


• ALT + u : uppercase one word after the cursor.


• CTRL + a : go to the first character of the line.


• CTRL + b : move back one character.


• CTRL + c : Sending signal SIGINT the current process you run (usually the process will be killed).


• CTRL + d : Sending EOF, Exit/logout the current shell.


• CTRL + e : go to the last character of the line.


• CTRL + f : move forward one character.


• CTRL + h : clear one character before the cursor. (similar with backspace)


• CTRL + k : cut all characters after the cursor.


• CTRL + l : clear screen.


• CTRL + r : search for previously used commands.


• CTRL + t : swap the last two characters before the cursor.


• CTRL + u : cut all characters before the cursor.


• CTRL + w : delete one word before the cursor.


• CTRL + y : recall the last cut character by CTRL+u or CTRL+k or ALT+d (just like paste)


• CTRL + z : put the current process you run into background process. To restore it, use command fg.


• ESC + t : swap the last two words before the cursor.


• TAB : autocomplete command/files or folders name.

That's all :)