Snippets of commands I use occasionally and tend to forget. Gets updated.
Count files in a directory
ls -1 . | wc -l
Count files in a directory recursively (all files in all sub-directories)
find . -type f | wc -l
Get information about a process
ps -u -p 12959
Get storage usage for directories
du -sh /home/*
Compress to .bz2
tar cjf file.tar.bz2 dir
Extracting .bz2
tar xvjf file.tar.bz2
Extracting .gz
tar xvzf file.tar.gz
Execute the same command N times in parallel
parallel -j $n_parallel $command ::: {1..$n_times}
If ‘-j’ is unspecified, defaults to number of cores.