How to mount qcow2 image
I’ve read that with qemu-nbd and the network block device kernel module, I can mount a qcow2 image. I haven’t seen any tutorials on mounting a qcow2 via a loop device. Is it possible? If not, why?
Unix & Linux
How to measure time of program execution and store that inside a variable
In order to find out how long certain operations within a Bash (v4+) script take, I would like to parse the output from the time command “separately” and (ultimately) capture it within a Bash variable (let VARNAME=...).
How to tell which keyboard was used to press a key?
I frequently work on pairing stations where there are multiple keyboards installed. I can use setxkbmap with -device <ID> to set the layout for a specific keyboard (using an ID from xinput), but often it’s not obvious which keyboard I’m at. It would be better to avoid the back-and-forth of trying both keyboards, so I’d like to write a quick tool to get this information for setxkbmap. I’d expect a typical use case like the following:
How can I replace a string in a previous command on the command-line?
I need to run a command, and then run the same command again with just one string changed.
Are limits.conf values applied on a per-process basis?
I’m tuning the nofile value in /etc/security/limits.conf for my oracle user and I have a question about its behavior: does nofile limit the total number of files the user can have open for all of its processes or does it limit the total number of files the user can have open for each of its processes?
How do I use command arguments with Cmnd_Alias in sudoers?
How do I specify command arguments in sudoers? As a background, aws command is actually a gateway to a whole bunch of sub-systems and I want to restrict the user to only run aws s3 cp ...any other args...
Calling multiple bash scripts and running them in parallel, not in sequence
Suppose that I have three (or more) bash scripts: script1.sh, script2.sh, and script3.sh. I would like to call all three of these scripts and run them in parallel. One way to do this is to just execute the following commands:
Use ssh with a specific network interface
I’m using openconnect to connect to vpn. After entering my credentials, I get this:
Counting occurrences of word in text file
I have a text file containing tweets and I’m required to count the number of times a word is mentioned in the tweet. For example, the file contains:
tail -f, but with line numbers
I’m trying to see how many times foo bar appears in /var/log/foo.log within an arbitrary amount of time on a remote server, but nothing that I’ve tried so far has worked.