Commands using echo (1,545)

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port scan using parallel
It takes over 5 seconds to scan a single port on a single host using nmap $ time (nmap -p 80 192.168.1.1 &> /dev/null) real 0m5.109s user 0m0.102s sys 0m0.004s It took netcat about 2.5 minutes to scan port 80 on the class C $ time (for NUM in {1..255} ; do nc -w 1 -z -v 192.168.1.${NUM} 80 ; done &> /dev/null) real 2m28.651s user 0m0.136s sys 0m0.341s Using parallel, I am able to scan port 80 on the entire class C in under 2 seconds $ time (seq 1 255 | parallel -j255 'nc -w 1 -z -v 192.168.1.{} 80' &> /dev/null) real 0m1.957s user 0m0.457s sys 0m0.994s

Find top 10 largest files in /var directory (subdirectories and hidden files included )
Should work even when very large files exist.

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

archive all files containing local changes (svn)
Create a tgz archive of all the files containing local changes relative to a subversion repository. Add the '-q' option to only include files under version control: $svn st -q | cut -c 8- | sed 's/^/\"/;s/$/\"/' | xargs tar -czvf ../backup.tgz Useful if you are not able to commit yet but want to create a quick backup of your work. Of course if you find yourself needing this it's probably a sign you should be using a branch, patches or distributed version control (git, mercurial, etc..)

zgrep across multiple files

Sort the size usage of a directory tree by gigabytes, kilobytes, megabytes, then bytes.
Probably only works with GNU du and modern perls.

Calculate the mean or average of a single column of numbers in a text file
single-column-numbers.txt is a text file with 22658 rows (numbers) in a single column. Each number can range from 0 to 134298679.533591 and the dot is for the decimals. This is done with perl because awk can't sum such high numbers.

Broadcast your shell thru ports 5000, 5001, 5002 ...
run 'nc yourip 5000', 'nc yourip 5001' or 'nc yourip 5002' elsewhere will produce an exact same mirror of your shell. This is handy when you want to show someone else some amazing stuff in your shell without giving them control over it.

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"

Undo commit in Mercurial


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