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Ping all hosts on 192.168.1.0/24
-b option takes the broadcast address.

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"

run command on a group of nodes in parallel redirecting outputs
Do the same as pssh, just in shell syntax. Put your hosts in hostlist, one per line. Command outputs are gathered in output and error directories.

Update all packages installed via homebrew

move you up one directory quickly
In bash, this turns on auto cd. If a command is just a directory name, it cd's into that directory.

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" }

kill ip connection
needed; apt-get install tcpkill

list files recursively by size

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

convert filenames in current directory to lowercase
The simplest way I know.


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