Commands by knassery (3)

  • Tshark to Generate Top Talkers by #TCP conv started per second.

    #_connects src_IP dst_IP When_It_Happened_Secs Show Sample Output


    -1
    tshark -qr [cap] -z conv,tcp | awk '{printf("%s:%s:%s\n",$1,$3,$10)}' | awk -F: '{printf("%s %s %s\n",$1,$3,substr($5,1,length($5)-10))}' | sort | uniq -c | sort -nr
    knassery · 2012-10-16 06:39:01 5
  • Show me a histogram of the busiest minutes in a log file:

    Busiest seconds: cat /var/log/secure.log | awk '{print substr($0,0,15)}' | uniq -c | sort -nr | awk '{printf("\n%s ",$0) ; for (i = 0; i<$1 ; i++) {printf("*")};}' Show Sample Output


    17
    cat /var/log/secure.log | awk '{print substr($0,0,12)}' | uniq -c | sort -nr | awk '{printf("\n%s ",$0) ; for (i = 0; i<$1 ; i++) {printf("*")};}'
    knassery · 2009-07-24 07:20:06 12
  • Graph # of connections for each hosts.

    Written for linux, the real example is how to produce ascii text graphs based on a numeric value (anything where uniq -c is useful is a good candidate). Show Sample Output


    54
    netstat -an | grep ESTABLISHED | awk '{print $5}' | awk -F: '{print $1}' | sort | uniq -c | awk '{ printf("%s\t%s\t",$2,$1) ; for (i = 0; i < $1; i++) {printf("*")}; print "" }'
    knassery · 2009-04-27 22:02:19 24

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a function to create a box of '=' characters around a given string.
First argument: string to put a box around. Second argument: character to use for box (default is '=') Same as command #4948, but shorter, and without the utility function.

Process command output line by line in a while loop
This snippet allows to process the output of any bash command line by line.

Remove annoying OS X DS_Store folders
Recursively removes all those hidden .DS_Store folders starting in current working directory.

C one-liners
$ /lib/ld-linux.so.2 is the runtime linker/loader for ELF binaries on Linux. =(cmd) is a zsh trick to take the output for the command "inside" it and save it to a temporary file. $ echo -e 'blah' | gcc -x c -o /dev/stdout - pipes the C source to gcc. -x c tells gcc that it's compiling C (which is required if it's reading from a pipe). -o /dev/stdout - tells it to write the binary to standard output and read the source from standard input. because of the the =() thing, the compiled output is stashed in a tempfile, which the loader then runs and executes, and the shell tosses the tempfile away immediately after running it.

GRUB2: Set Imperial Death March as startup tune
Kudos to http://www.commandlinefu.com/commands/view/8275/grub2-set-super-mario-as-startup-tune

List hostnames of all IPs

Print all lines between two line numbers
This command uses awk(1) to print all lines between two known line numbers in a file. Useful for seeing output in a log file, where the line numbers are known. The above command will print all lines between, and including, lines 3 and 6.

Bash logger

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.

grep (or anything else) many files with multiprocessor power
Parallel does not suffer from the risk of mixing of output that xargs suffers from. -j+0 will run as many jobs in parallel as you have cores. With parallel you only need -0 (and -print0) if your filenames contain a '\n'. Parallel is from https://savannah.nongnu.org/projects/parallel/

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