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Find number of computers in domain, OU, etc .

chroot, bind mount without root privilege/setup
PRoot is a user-space implementation of chroot, mount --bind, and binfmt_misc. This means that users don't need any privileges or setup to do things like using an arbitrary directory as the new root filesystem, making files accessible somewhere else in the filesystem hierarchy, or executing programs built for another CPU architecture transparently through QEMU user-mode. Also, developers can use PRoot as a generic Linux process instrumentation engine thanks to its extension mechanism, see CARE for an example. Technically PRoot relies on ptrace, an unprivileged system-call available in every Linux kernel. https://github.com/cedric-vincent/PRoot

Check if the Debian package was used since its installation/upgrade.
This script compares the modification date of /var/lib/dpkg/info/${package}.list and all the files mentioned there. It could be wrong on noatime partitions. Here is non-oneliner: #!/bin/sh package=$1; list=/var/lib/dpkg/info/${package}.list; inst=$(stat "$list" -c %X); cat $list | ( while read file; do if [ -f "$file" ]; then acc=$(stat "$file" -c %X); if [ $inst -lt $acc ]; then echo used $file exit 0 fi; fi; done exit 1 )

drop first column of output by piping to this

python2 -m CGIHTTPServer
In case you need to test some CGI scripts this does the job. It also has the functionality of a http server. Enjoy!

Find the package that installed a command

list files recursively by size

Converts all pngs in a folder to webp using all available cores
As an alternative to the above command, this one ditches the unnecessary and complicated for loop in favor of a way faster multi-core approach for a task that's more CPU than I/O intensive, making it a perfect suite for GNU parallel

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"


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