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deaggregate ip ranges
Taking file with ip ranges, each on it's own line like: $cat ipranges.txt 213.87.86.160-213.87.86.193 213.87.87.0-213.87.88.255 91.135.210.0-91.135.210.255 command returns deaggregated ip ranges using ipcalc deaggregate feature like that: 213.87.86.160/27 213.87.86.192/31 213.87.87.0/24 213.87.88.0/24 91.135.210.0/24 Useful for configuring nginx geo module

Prevent shell autologout
Unset TMOUT or set it to 0 in order to prevent shell autologout. TMOUT is the number of seconds after which the present shell will be killed if it has been idle for that long.

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

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" }

Access folder "-"
If you try to access cd - you go to the last folder you were in.

Installing debian on fedora (chrooted)

View dmesg output in human readable format

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"

Display condensed log of changes to current git repository
Assuming you are working within a git repository, you can run the above command & see what has changed in reverse chronological order, with one commit per line. Other formatting variations to 'oneline' include 'short', 'medium', 'full', 'fuller', 'email' or 'raw'.

Create QR codes from a URL.
QR codes are those funny square 2d bar codes that everyone seems to be pointing their smart phones at. Try the following... $ qrurl http://xkcd.com Then open qr.*.png in your favorite image viewer. Point your the bar code reader on your smart phone at the code, and you'll shortly be reading xkcd on your phone. URLs are not the only thing that can be encoded by QR codes... short texts (to around 2K) can be encoded this way, although this function doesn't do any URL encoding, so unless you want to do that by hand it won't be useful for that.


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