Problem
You would like to find out the serial number of your Lenovo laptop, but without switching it off and taking the battery off.
Solution
You can run the following to get your laptop’s details including the serial number:
sudo dmidecode -t system
Taken from the post here
Problem
You have a remote server (Debian) running some Docker containers and you want to make sure that they all restart in the event of a kernel panick.
solution
sysctl kernel.panic=20
echo c > /proc/sysrq-trigger
Problem
Looking at your /var/log/syslog you see entries every few seconds like the following:
Mar 1 15:44:52 L530 systemd-udevd[11464]: failed to execute '/lib/udev/socket:@/org/freedesktop/hal/udev_event' 'socket:@/org/freedesktop/hal/udev_event': No such file or directory Mar 1 15:44:52 L530 systemd-udevd[11451]: Process 'socket:@/org/freedesktop/hal/udev_event' failed with exit code 2. Mar 1 15:44:54 L530 systemd-udevd[11479]: failed to execute '/lib/udev/socket:@/org/freedesktop/hal/udev_event' 'socket:@/org/freedesktop/hal/udev_event': No such file or directory Mar 1 15:44:54 L530 systemd-udevd[11466]: Process 'socket:@/org/freedesktop/hal/udev_event' failed with exit code 2.
Solution
Seems that hal is not used in newer Ubuntu versions, so you can remove it:
sudo apt-get purge hal
Taken from the answer here
Problem
You want to remove a certain line from your server’s bash history, if for example you pasted a password in the wrong place.
Solution
Use the two steps:
1. history -d line_number to remove from memory
2. history -w to write in-memory history to the history file ~/.bash_history
as described here
When the shell is not bash (sh) you can remove them from ~/.ash_history and then source the file.
Problem
You would like to change the default editor for crontab from nano to vim.
Solution
Add the following to the ~/.selected_editor:
SELECTED_EDITOR="/usr/bin/vim"
or run the select-editor and choose vim-basic (4)
server# select-editor Select an editor. To change later, run 'select-editor'. 1. /bin/ed 2. /bin/nano <---- easiest 3. /usr/bin/mcedit 4. /usr/bin/vim.basic 5. /usr/bin/vim.tiny Choose 1-5 [2]: 4
Problem
When trying to configure nullmailer you may end up with many test emails that end up in the queue, that you don’t want to keep trying to send, but to delete them.
Solution
Clear the nullmailer queue by running:
rm /var/spool/nullmailer/queue/*
Problem
You would like to quickly convert a number from a different base system (i.e. binary, octal, hexadecimal), to decimal.
Solution
Use the echo $(()) shell command to convert it passing it the current base system and the number, as in $((2#101010)) or using the O for octal or 0x for hexadecimal notations.
Examples:
echo $(( 16#FF )) 255 echo $(( 0xFF )) 255 echo $(( 8#21 )) 17 echo $(( 021 )) 17
Taken from Linux Journal’s Work the Shell column (March 2016)
Problem
You have received multiple zip files that were originally one big zip file, possibly from windows, and you want to put them back together and unzip them in linux.
Solution
So if your file names are for example called: file1.zip file2.zip etc, you can do the following:
cat file* > one_file.zip unzip one_file.zip
Problem
You have a Xen virtual machine and the system clock regularly drifts off daily (not synchronised).
Solution
Use the instructions from here to synchronise the VM clock with the host.
Problem
You are given a patch file to apply to your git repository but using git apply does not work. No errors reported but no changes applied neither.
Solution
Try to use the patch command command possibly with the -p1 parameter like:
patch -p1 < path_to_the_patch_file.patch
NOTE: Make sure that you are in the right folder relative to the file path in the patch file