There is a not very well known bash command that allows you to repeat the last input you typed in the shell. Behold the “!!” command. This simply allows us to retype the last input. For instance: If I type: (to list files in the local directory): ls -lh and after that I type: !! […]
GNU – Shred
Have you ever wanted to delete “permanently” a file from your file system?. Well, you can do it with this command: shred . First, a litle about how a file system works. Simply put, the system keeps a table with references to each file. When you delete a file what really happens is that the […]
About e-readers devices
This text is a litle rant about e-readers. First, I would like to state the pros: Not having to carry my books everywhere is very convenient, I can have my administration/programming/whatever books easily accesible in a single weightless device. Battery last weeks (depends on usage) Able to write notes, which is also very convenient Many […]
GNU – duf
This can be seen as an improvement of the classical command df, that allows us to show the file system disk space usage. If you type df -h (the h option is for human readable) it will show you something like this: tmpfs 1,6G 2,8M 1,6G 1% /run/dev/nvme0n1p2 468G 222G 223G 50% /tmpfs 7,8G 0 […]
GNU – pwd
Have you ever wondered how to get the path of the working directory?. To do that you can use the command: PWD . This simple order gives you precisely that, the working directory, for instance: pwd > returns /home/user/dir As always use the man command to get more info about the inner details of this […]
GNU – pushd/popd
This couple of commands are really helpful. It allows you to easily navigate through the system without having to repeat long paths. For example, imagine that you are in the directory /user/data/data2/home/ but want to change to other directory for a moment, say /etc ; you can do: pushd /etc -> this will move to […]
Gnu – Flock
This is an interesting command. Have you ever wanted to be sure that just one instance of your app/script is running at the same time? Then, flock is your tool. The sintax is as follows: flock [options] file|directory command [arguments] Lets see an example: flock /home/user/lockfile htop This runs htop and uses a generated file […]
Gnu – Timeout
This is one of those extremely useful commands that not many people know. Basically runs a shell command and exits when the time runs out. The format is as follows: timeout [OPTION] DURATION COMMAND [ARG]… Lets see an example: timeout 10s top : This starts the top utility waits for 10 seconds and quit. Simple. […]
Gnu – w
Have you ever wonder who is in your system? and doing what? Well, beauty always comes in small packages and today it is not an exception, the only thing you need is: w .This small tool comes to the rescue. The format is as follows: w [options] user […] Lets see some examples: w -> […]
Gnu – ls
This command allows you to list files and directories (dir in Ms-dos world). Lets see how this works. The format is as follows: ls [OPTION]… [FILE]… You can type ls as is to show a barebones listing of files and directories. Lets see more possibilities: ls -l -> this shows the long listing format (its […]