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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" }

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Move all files between to date
In a folder with many files and folders, you want to move all files where the date is >= the file olderFilesNameToMove and

VMware Server print out the state of all registered Virtual Machines.
I use this command on my machines running VMware Server to print out the state of all registered Virtual machines.

List your largest installed packages (on Debian/Ubuntu)

List all files/folders in working directory with their total size in Megabytes

Start a command on only one CPU core
This is useful if you have a program which doesn't work well with multicore CPUs. With taskset you can set its CPU affinity to run on only one core.

Equivalent to ifconfig -a in HPUX
not shown ifconfig error

List 10 largest directories in current directory
du -m option to not go across mounts (you usually want to run that command to find what to destroy in that partition) -a option to also list . files -k to display in kilobytes sort -n to sort in numerical order, biggest files last tail -10 to only display biggest 10

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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