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Display the human-readable sizes of all files and folders in the current directory with 3 decimal places
To sort the list by file/directory size, insert `sort -n |` before `awk`.

Sniffing network to generate a pcap file in CLI mode on a remote host and open it via local Wireshark ( GUI ).
Then hit ^C to stop, get the file by scp, and you can now use wireshark like this : $ wireshark /tmp/sniff.pcap If you have tshark on remote host, you could use that : $ wireshark -k -i

Determine the version of a specific package with RPM
In this case, I'm getting the package version for 'redhat-release', but of course, this can be applied to any package installed on the filesystem. This is very handy in scripts that need to determine just the version of the package, without the package name and all the sed and grep hackery to get to the data you want. To find out all the support format strings that 'rpm --qf' supports: $ rpm --querytags

Cleanup a (source) text file, removing trailing spaces/tabs and multiple consecutive blank lines
I used this command (in addition to a code formatting tool) to "cleanup" a bunch of PHP files

Benchmark SQL Query
Benchmark a SQL query against MySQL Server. The example runs the query 10 times, and you get the average runtime in the output. To ensure that the query does not get cached, use `RESET QUERY CACHE;` on top in the query file.

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"

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Find all plain text files that do not contain STRING

open two files on top of each other in vim (one window, two panes)

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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