Commands by varenc (2)

  • Realtime lines per second in a log file, with history

    This is similar to standard `pv`, but it retains the rate history instead of only showing the current rate. This is useful for spotting changes. To do this, -f is used to force pv to output, and stderr is redirected to stdout so that `tr` can swap the carriage returns for new lines. (doesn't work correctly is in zsh for some reason. Tail's output isn't redirected to /dev/null like it is in bash. anyone know why? ???????) Show Sample Output


    1
    tail -f access.log | pv -l -i10 -r -f 2>&1 >/dev/null | tr /\\r \ \\n
    varenc · 2020-04-19 02:07:40 100
  • Random number with a normal distribution between 1 and X

    Print a random number between 1 and 50 with a normal distribution around the center. The numbers around the middle are the most likely to occur and the farther you get from that the less and less common they are. You can test this and observe the number distribution with this command: for i in `seq 100000`; do echo $[(${RANDOM}%40+${RANDOM}%40)/2+1]; done | sort -n | uniq -c Show Sample Output


    0
    echo $[(${RANDOM}%100+${RANDOM}%100)/2+1]
    varenc · 2019-05-16 00:58:25 43

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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.

Block all IP addresses and domains that have attempted brute force SSH login to computer
I use iptables. To rate limit connections. Very easy and no ban lists to manage.

Recursive grep of all c++ source under the current directory

This command will help you to hunt the current mysql query statement in real time. (-R is deprecated, using updated -Y)

Show a Package Version on Debian based distribution
if you don't want to show string "version?, then use awk or cut filter it: apt-cache show pkgname | grep -i "version:" | awk '{ print $2 }' we can also use regex to search many packages and show their versions: apt-cache search pkgregex | grep -i "version:"

delete multiple files with spaces in filenames (with confirmation)
ls -Q will show the filenames in quotes. xargs -p rm will print all the filenames piped from ls -Q and ask for confirmation before deleting the files. without the -Q switch, if we have spaces in names, then the files won't be deleted.

Count opening and closing braces in a string.
This function counts the opening and closing braces in a string. This is useful if you have eg long boolean expressions with many braces and you simply want to check if you didn't forget to close one.

Print a random 8 digit number
Don't need to pipe the output into rs if you just tell jot to use a null separator character.

Easily find latex package documentation
If the pdf/dvi/etc documentation for a latex package is already part of your local texmf tree, then texdoc will find and display it for you. If the documentation is not available on your system, it will bring up the package's webpage at CTAN to help you investigate.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

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