Commands by Vadi (1)

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Show the 20 most CPU/Memory hungry processes
This command will show the 20 processes using the most CPU time (hungriest at the bottom). You can see the 20 most memory intensive processes (hungriest at the bottom) by running: $ ps aux | sort +3n | tail -20 Or, run both: $ echo "CPU:" && ps aux | sort +2n | tail -20 && echo "Memory:" && ps aux | sort +3n | tail -20

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

resolve short urls
since the most url shorteners respond with a header containing the Location: ... this works with most common shorteners

Listing directory content of a directory with a lot of entries
Ever wanted to get the directory content with 'ls' or 'find' and had to wait minutes until something was printed? Perl to the rescue. The one-liner above(redirected to a file) took less than five seconds to run in a directory with more man 2 million files. One can adapt it to e.g. delete files that match a certain pattern.

print line and execute it in BASH
!# is the currennt line so far, by using !#:- you can go from the second arg (it's zero indexed) to the last ($) (did I understand the problem correctly?)

Check if a process is running
Send signal 0 to the process. The return status ($?) can be used to determine if the process is running. 0 if it is, non-zero otherwise.

Copy a MySQL Database to a new Server via SSH with one command
Dumps a MySQL database over a compressed SSH tunnel and uses it as input to mysql - i think that is the fastest and best way to migrate a DB to a new server!

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

find an unused unprivileged TCP port
perl-less way

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.


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