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random xkcd comic
i sorta stole this from http://www.shell-fu.org/lister.php?id=878#MTC_form but it didn't work, so here it is, fixed. --- updated to work with jpegs, and to use a fancy positive look behind assertion.

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

Skip banner on ssh login prompt
This allows you to skip the banner (usually /etc/issue.net) on ssh connections. Useful to avoid banners outputted to your mail by rsync cronjobs.

a function to find the fastest DNS server
http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list.

Remove invalid host keys from ~/.ssh/known_hosts
Useful if you have to tunnel ssh through a local port and it complains of the host key being different. Much easier than manually editing the file.

Get the IP address of a machine. Just the IP, no junk.
Why use many different utilities all piped together, when you only need two?

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 the package that installed a command

Automator Bash script to create Clean zips in MacOS Finder without __MACOSX metadata
Finder compresses to ZIP but always includes extraneous metadata files (__MACOSX and .DS_Store) files and folders that may confuse other programs. One alternative is creating them and then editing the ZIP. This can work standalone or in an automator script accepting multiple selections (files or folders) and creating one zip per argument/selected file without that metada.


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