Have you ever wanted to know the type of a file?. You can with the file command. For example, the command:
file archive.pdf
will return something like:
archive.pdf: PDF document, version 1.5
easy and very helpful. As always, check the man pages for more information.
Have you ever wanted to know how good or bad is your battery health? You do not want to install complex programs to get that info. Think no more, because Upower comes to the rescue. This nice tool allows you to get information about your battery, showing you a very nice report about it. Just type:
upower -e
to list all avalaible devices. And type:
upower -i "device"
to get a report
As always, for more information read the man pages.
This is an impressive cli command. It does a simple task: show a file content progressively, that is to say, one page at a time. If the file is big this utility is faster than more because it does not have to load the entire file at once, just the first page. You can acces the rest of the document page by page with its own pager system, as if it was a text reader like vim or emacs. The basic sintax is :
less "filename"
You can do a ton of things with this utility. The man documentation shows hundreds of options and posibilities. For instance:
less "filename" -p "text to start"
command will allow you to open file «filename» and start showing the content when the text «text to start» is found.
As always, check the man page for more information and options, but be aware that this utility is huge in terms of posibilities.
This is a simple command. It give us the system information. It has a few options, as:
uname -a -> shows all info
uname - v -> shows kernel version
uname - o -> shows operating system version
There are many options, so as always, check the man pages for more info.
This simple command is able to do a few things. If you read the man description it will tell you this:
touch - change file timestamps
so basically this tool changes the timestamp of a file, but it can also do:
A FILE argument that does not exist is created empty, unless -c or -h is supplied
which is what people usually use this command for. So the next time you need to create an empty file, in a fast and simple way, just type:
touch filename
and a new empty file named filename will be created for you. As allways check the man page for more information
Have you ever wondered what is taking so much space in your hard drives? You have thousands of files but you dont know what is what or where are the biggest files. Well, sometimes you need a way to know what is inside your hard drive. You can achieve this with a beautiful and useful utility: ncdu
Simply type
ncdu /
and you will get something like this:
88,6 MiB [##########] dockerd
57,8 MiB [###### ] docker
40,9 MiB [#### ] containerd
30,7 MiB [### ] x86_64-linux-gnu-lto-dump-12
23,7 MiB [## ] x86_64-linux-gnu-lto-dump-11
23,3 MiB [## ] ctr
19,6 MiB [## ] containerd-stress
15,4 MiB [# ] snap
15,1 MiB [# ] qemu-system-x86_64
15,0 MiB [# ] qemu-system-i386
9,8 MiB [# ] gdb
9,6 MiB [# ] gimp-2.10
8,0 MiB [ ] gtk4-encode-symbolic-svg
7,7 MiB [ ] rustdoc
7,7 MiB [ ] containerd-shim-runc-v2
7,7 MiB [ ] containerd-shim-runc-v1
7,3 MiB [ ] ctest
6,5 MiB [ ] qemu-system-x86_64-microvm
6,4 MiB [ ] cmake
That way you have a good representation of every part of your file system. In some distros you need to install the utility as is not installed by default. As always check the man pages for more info.
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:
!!
It will repeat the «ls -lh» command.
This comes in handy when you want to script bash in a file. You can also add regex expressions. Imagine you forgot to include the hidden files in your listing, you can replace «lh» with «lha»
!!:s/lh/lha
As always, feel free to experiment. And do not forget to check the documentation.
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 operating system removes the reference to the file from the table of references, but the data is still there, so is possible to recover the data. If you really want to delete a file you can use shred. This utility overwrite with random data the file so its unrecoverable. Example: (the u option deletes the file after overwriting)
shred -u filename
As always, see the documentation for more options and use cases.
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 7,8G 0% /dev/shm
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
tmpfs 7,8G 0 7,8G 0% /run/qemu
/dev/nvme0n1p1 511M 5,3M 506M 2% /boot/efi
Nice, but a bit clunky. Instead if you use duf, you will see something like this:
╭──────────────────────────────────────────────────────────────────────────────────────────────────────╮ │ 3 local devices │ ├───────────────────┬────────┬────────┬────────┬───────────────────────────────┬──────┬────────────────┤ │ MOUNTED ON │ SIZE │ USED │ AVAIL │ USE% │ TYPE │ FILESYSTEM │ ├───────────────────┼────────┼────────┼────────┼───────────────────────────────┼──────┼────────────────┤ │ / │ 467.9G │ 221.9G │ 222.2G │ [#########...........] 47.4% │ ext4 │ /dev/nvme0n1p2 │ │ /boot/efi │ 511.0M │ 5.2M │ 505.7M │ [....................] 1.0% │ vfat │ /dev/nvme0n1p1 │ │ /media/user/disc │ 457.1G │ 333.2G │ 100.6G │ [##############......] 72.9% │ ext4 │ /dev/sda2 │ ╰───────────────────┴────────┴────────┴────────┴───────────────────────────────┴──────┴────────────────╯ ╭────────────────────────────────────────────────────────────────────────────────────────────────╮ │ 7 special devices │ ├────────────────┬──────┬────────┬───────┬───────────────────────────────┬──────────┬────────────┤ │ MOUNTED ON │ SIZE │ USED │ AVAIL │ USE% │ TYPE │ FILESYSTEM │ ├────────────────┼──────┼────────┼───────┼───────────────────────────────┼──────────┼────────────┤ │ /dev │ 7.7G │ 0B │ 7.7G │ │ devtmpfs │ udev │ │ /dev/shm │ 7.7G │ 0B │ 7.7G │ │ tmpfs │ tmpfs │ │ /run │ 1.5G │ 2.8M │ 1.5G │ [....................] 0.2% │ tmpfs │ tmpfs │ │ /run/lock │ 5.0M │ 4.0K │ 5.0M │ [....................] 0.1% │ tmpfs │ tmpfs │ │ /run/qemu │ 7.7G │ 0B │ 7.7G │ │ tmpfs │ tmpfs │ │ /run/snapd/ns │ 1.5G │ 2.8M │ 1.5G │ [....................] 0.2% │ tmpfs │ tmpfs │ │ /run/user/1000 │ 1.5G │ 140.0K │ 1.5G │ [....................] 0.0% │ tmpfs │ tmpfs │ ╰────────────────┴──────┴────────┴───────┴───────────────────────────────┴──────────┴────────────╯
Which is a much better way to see the information. As always check the man page for more info about this command.
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 easy but useful tool.
