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Number of CPU's in a system
This appears to do the same. Utility is verified to be present on Ubuntu and OpenSuse out-of-the-box.

Display kernel profile of currently executing functions in Solaris.
Lockstat will sample the kernel 977 times per second, and print out the functions that it sees executing on the CPU during the sample. The -s 10 switch tells lockstsat to not only print that function, but also show the call stack (up to 10 deep).

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Rename many files in directories and subdirectories
This is probably overkill, but I have some issues when the directories have spaces in their names. The $ find . -type d -print0 | while read -d $'\0' dir; do xxx; done loops over all the subdirectories in this place, ignoring the white spaces (to some extend). $ cd "$dir"; echo " process $dir"; cd -; goes to the directory and back. It also prints some info to check the progress. $ find . -maxdepth 1 -name "*.ogg.mp3" -exec rename 's/.ogg.mp3/.mp3/' {} \; renames the file within the current directory. The whole should work with directories and file names that include white spaces.

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"

validate json
I have this saved as jsonlint chmodded +x and file.js is instead $1, but YMMV

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"

Get all available packages on Ubuntu (or any distro that uses apt)

Deal with dot files safely

Create a file of a given size in linux
If you're trying to create a sparse file, you can use dd by 'skip'ing to the last block instance. ls -ls shows the actual size vs. the reported size


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