# Common used command lines
1. `pwd`: present working directory, to show current position
2. `ls`: list the contents, to show the list of files
3. `cd`: change directories, used for going to certain folder/file. e.g. `cd ~/desktop/`-> go to desktop
4. `cd ..`: go back to the previous directory
5. `touch`: to create a new file: `touch tryout.txt`
6. `cat(1)`: display the content of the file: `cat tryout.txt`
` cat(2)`: to create a new file: `cat > aNewFile.txt`
`cat(3)`: to concatenate two files:` cat tryout1.txt tryout2.txt > tryout3.txt`
note: There are still a bunch of usages of 'cat', it's a powerful and complex tool!
6. `mkdir`: make a directory: `mkdir kk`->then create a folder called kk
7. `rmdir`: remove a directory: rmdir kk->then delete the given folder kk
8. `rm`: remove a file: rm tryout.txt
9. `clear`: clear the current page(not delete, just present a clean page)
10. `control+c`: to end a command