This is a very interesting bash shell trick. You may use the !! operator to allow editing a misspelled command in your bash history and rerun it correctly. This allows for fixing an error you made with a previous command as shown below.
[ jason@$deusexmachina.local ] [ Jobs 0. PWD: ~. -bash 3.2.57. ] [ 32-:$ ] -> ehco hello -bash: ehco: command not found |
As we can see here this is easy to fix.
[ jason@$deusexmachina.local ] [ Jobs 0. PWD: ~. -bash 3.2.57. ] [ 35-:$ ] -> !!:gs/ehco/echo/ echo hello hello |
This reruns the command and it is spelled correctly. This is a nifty feature of the bash shell. This allows easy correction of mistakes with no fuss at all.
Print a directory listing of only folders in the current directory using ls.
[ jason@$deusexmachina.local ] [ Jobs 0. PWD: ~. -bash 3.2.57. ] [ 37-:$ ] -> ls -dhula */ drwx------@ 75 jason staff 2.3K 10 Apr 15:27 Desktop/ drwx------@ 75 jason staff 2.3K 10 Apr 16:53 Documents/ drwx------@ 48 jason staff 1.5K 10 Apr 08:54 Downloads/ drwx------@ 84 jason staff 2.6K 3 Apr 10:32 Library/ drwx------+ 6 jason staff 192B 30 Mar 17:06 Movies/ drwx------+ 16 jason staff 512B 10 Apr 15:27 Music/ drwx------+ 12 jason staff 384B 10 Apr 16:46 Pictures/ drwxr-xr-x+ 5 jason staff 160B 2 Jan 2019 Public/ drwxr-xr-x 9 jason staff 288B 8 Apr 15:12 Videos/ |
The ls -dhula */ command is the best way to do this.
Another way is to only list directories with the bash shell. Just use the find command and ls.
[ jason@$deusexmachina.local ] [ Jobs 0. PWD: ~. -bash 3.2.57. ] [ 53-:$ ] -> find . -name *. -maxdepth 1 -type d -exec ls -dhula */ {} + drwxr-xr-x+ 54 jason staff 1.7K 11 Apr 11:18 . drwx------@ 75 jason staff 2.3K 10 Apr 15:27 Desktop/ drwx------@ 75 jason staff 2.3K 10 Apr 16:53 Documents/ drwx------@ 48 jason staff 1.5K 10 Apr 08:54 Downloads/ drwx------@ 84 jason staff 2.6K 3 Apr 10:32 Library/ drwx------+ 6 jason staff 192B 30 Mar 17:06 Movies/ drwx------+ 16 jason staff 512B 10 Apr 15:27 Music/ drwx------+ 12 jason staff 384B 10 Apr 16:46 Pictures/ drwxr-xr-x+ 5 jason staff 160B 2 Jan 2019 Public/ drwxr-xr-x 9 jason staff 288B 11 Apr 11:47 Videos/ |
This will list all folders on one level under the current working directory. A very useful Linux trick.
Display an ANSI colour palette with the bash shell. Very useful to see all available bash colours.
e="\033[" for f in 0 7 `seq 6`; do no="" bo="" for b in n 7 0 `seq 6`; do co="3$f"; p=" " [ $b = n ] || { co="$co;4$b";p=""; } no="${no}${e}${co}m ${p}${co} ${e}0m" bo="${bo}${e}1;${co}m ${p}1;${co} ${e}0m" done echo -e "$no\n$bo" done |
This prints all colour codes for making a nice colour prompt. This is a useful way to get a certain colour you need.
Print information about your user with the id command.
[ jason@$deusexmachina.local ] [ Jobs 0. PWD: ~. -bash 3.2.57. ] [ 64-:$ ] -> id -P $LOGNAME jason:********:501:20::0:0:John Cartwright:/Users/jason:/bin/bash |
This prints the user information as a password file entry. Very interesting to see in action.