1. Source command
Source command executes the contents of the file which is passed as the argument to it
Sample
Let’s say we have two Java versions — Java 8 & Java 11
We often switch between the versions by changing the JAVA_HOME in ~/.bash_profile
If we edit the ~/.bash_profile file, we need to restart our terminal for the changes to reflect
But with source command, we can see the changes reflect in current terminal session itself. Just do
> source ~/.bash_profile2. Tree command
Most of us are familiar with tree command which displays content of a directory in a tree-like format
But there can be a scenario where you may want to skip few folders as they have so many files in it. Best example is node_modules folder in Node based applications
So lets see how to ignore a folder in tree command
// For ignoring single folder
> tree -I Docker// For ignoring folders which match the regex
> tree -I Dock*// For ignoring multiple folders in single command
// Double quotes are mandatory for this
> tree -I "Dock*|Kubernetes"
Refer to other interesting tree command flags here — https://www.computerhope.com/unix/tree.htm
3. Sudo Previous Command
Sometimes the command we run fails because of lack of permission. The obvious solution would be to run the same command with sudo prefix
But do we really need to edit the previous command and add the sudo prefix to it ? We don’t have to
You can do sudo !! command which will rerun the previous command with sudo prefix
4. History Command
history command is a familiar for most of us. Thats how at least I manage to survive in this industry with such poor memory power
history command list down all previous commands we run in terminal
// Sample output for history command
> history540 clear541 sudo ~/.bash_profile542 vi ~/.bash_profile
Let’s say we want to rerun the command vi ~/.bash_profile from above result. We don’t have to copy paste the command again
Simply run
> !542542 is the number given for vi ~/.bash_profile command
Note: All commands listed by history command are numbered
We can also search for a particular command among history by doing grep on history command
> history | grep bash_profile5. Alias Command
Alias command help us avoid typing lengthy commands again and again
Let’s say we often edit .bash_profile with sudo vi ~/.bash_profile
Instead of typing the command every time, we can create an alias for it
// Created alias called bedit
> alias bedit='sudo vi ~/.bash_profile'// we can simply run bedit hereafter
> bedit// If you want to remove the alias
> unalias bedit
Thats all folks !
