Posts by Iizuki
An exclamation mark followed by space in the beginning of a pipeline will negate the final exit code of the pipeline. Here's an example in Bash. Echoing $? will print out the exit code of the prev...
dmidecode can do this. Here's an example output from my system: # dmidecode --type 2 Getting SMBIOS data from sysfs. SMBIOS 3.1.1 present. Handle 0x0002, DMI type 2, 15 bytes Base Board Info...
How to apply a logical not to a shell command, e.g. in a Bash script? So if the command exited with 0 (success) I would like it to be changed to a non-zero value, and if it exited with a non-zero ...
ip a command will conveniently show the addresses assigned to your network interfaces, but oftentimes this is not what the internet sees your machine as. So how to find your public IP address from...
How to get the number of lines in a file? I.e. for a file like this: Line one Line 2 Final line I would like to do something like this: $ count-lines /path/to/the/file/above 3
How to convert a json file to yaml? Technically json is already valid yaml, but I'm talking about the characteristic easy-to-read yaml formatting with indentation and minimal quotes.
xmllint from xmllib2 can do this: $ output-dirty-xml | xmllint --format - The dash in the end tells xmllint to read from stdin instead of a file. Source: manpage
How to configure ZSH shell to print a timestamp on the right hand side of the prompt line when executing a command? I don't want to display the time prior to executing a command. Here's about how ...
The preexec function is called right before executing commands, so it's the place to do this sorta things. This solution is adapted from Dan Berindei's original answer (CC BY-SA 3.0) to a related ...
Surely there exists a command to print out the system's mother board model? Opening up the chassis is not an option.
Sometimes your programs fail because the network port they are trying to use is already in use by some other process. How to find out what this other process is?
Desktop files always have either %u or %U as an argument for the program being launched. E.g. here's a line from my firefox.desktop: Exec=/usr/lib/firefox/firefox %u What does it mean?
They are defined in the Desktop Entry Specification. In fact there are also %f and %F options. They tell the desktop manager how the program handles multiple files. Like if I select a bunch of fil...
With yq: $ yq --output-format yaml . file.json > file.yaml . is a filter which is applied to the data, but since . just stands for the document root, this means that the data is passed throu...
I have no experience with dunst, but generally you want a global service-level dropin file in /etc/systemd/system/service.d/ with OnFailure= setting in it. This way it gets added to all services ru...
There's a sha1sum tool in GNU coreutils: $ touch file $ sha1sum file da39a3ee5e6b4b0d3255bfef95601890afd80709 file Note the trailing spaces and the filename in the output. It needs to be acc...
Yup that's the recommended way to do it. Wants adds the network-online.target as a soft dependency.[1] Systemd will try to start it if it isn't up already. Networking should work after this target...
At the moment GPG only offers the following options when generating a new subkey the with the addkey command: gpg> addkey Please select what kind of key you want: (3) DSA (sign only) (...
This is how to save it to a file: $ gpg --export --armor key-id > my-key.pub --armor stands for the format with printable characters.
Here's the relevant ArchWiki page. The gist of it is that most of those warnings are probably for some fairly obscure hardware, and can be just ignored (provided that your system indeed works fine...
How to pretty print XML in a shell? I have command-line tool which outputs XML in a single line, totally unreadable. I would like something to pipe this into, to turn it into human readable XML wi...
This can be done by setting the LDAPTLS_REQCERT environment variable to never. For example like this when issuing the command: LDAPTLS_REQCERT=never ldapsearch -H ldaps://example.com:636 ...
One way is to use grep: $ grep --count ^ /path/to/the/file The ^ character matches a start of a new line, so it basically counts the number of starting lines.
How to open a port when using firewalld as the system firewall?
By using the non-interactive --quick-add-key method. This adds separate signing and encryption subkeys with expiration date one year from now: $ gpg --quick-add-key YOUR-PRIMARY-KEY-ID ed25519 sig...
