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afl-launch is a simple program to spawn afl fuzzing instances from the command line. It provides no compelling features; it is simply my version of this tool.

Usage of afl-launch:
        [HACK] substitute XXX in the target args with an 8 char random string [HACK]
  -f string
        Filename template (substituted and passed via -f)
  -i string
        afl-fuzz -i option (input location)
  -m string
        afl-fuzz -m option (memory limit), 'none' for no limit (defaults to afl)
  -n int
        Number of instances to launch (default 1)
  -name string
        Base name for instances. Fuzzers will work in <output>/<BASE>-[M|S]<N>
        Launch all instances with -S
  -o string
        afl-fuzz -o option (output location)
  -t string
        afl-fuzz -t option (timeout)
  -x string
        afl-fuzz -x option (extras location)

The launcher DOES NOT CHECK if the afl-fuzz instance errored out. Before starting a multiple launch, you should start afl-fuzz once manually with your desired -i -o -x (etc) options to make sure everything works.

If you don't supply a base name, the launcher will pick a random one.


./afl-launch -i ~/testcases/pdf -o ~/fuzzing/pdf -n 4  -- pdftoppm @@

A note on the -f flag - the idea is that you pass a template like /dev/shm/whatever.xml and the launcher will substitute it as -f /dev/shm/<BASENAME>-S12.xml when it invokes afl-fuzz. This is so that you can have AFL create testcase files on a ramdisk, and avoid stressing your disks. Queue entries and crashes are still saved as usual in the location specified by -o. Don't be an idiot like me and run everything on a ramdisk.

Another note about ttys - this tool just spawns all the processes and then exits. If you want them to stay running unattended then the easiest and (IMHO) best way is just to run it inside a screen session (man screen).


There is a hacky option that can be used for a few things. If you pass -XXX then the literal string XXX anywhere in the target command (after the -- in the command line) will be replaced with a random 8 character string. I use this for targets that require a -o flag for output filename, like stupidprogram -i @@ -out /dev/shm/XXX.jpg.

They launched.. now what?

Use afl-whatsup <LOCATION> with the same location you used for -o to get the afl-fuzz summary output. For bonus points, be a unix nerd and do like watch -n 60 afl-whatsup -s ~/fuzzing/targetname

This is what that looks like:

Every 60.0s: afl-whatsup -s ~/fuzzing/targetname Sun Jun  7 10:40:36 2015

status check tool for afl-fuzz by <>

Summary stats

       Fuzzers alive : 40
      Total run time : 161 days, 22 hours
         Total execs : 4513 million
    Cumulative speed : 12904 execs/sec
       Pending paths : 75 faves, 29250 total
  Pending per fuzzer : 1 faves, 731 total (on average)
       Crashes found : 9806 locally unique


You should follow the instructions to install Go, if you haven't already done so.

Download, build and install afl-launch:

$ go get -u


Nothing on the list. Open an issue if you want something.


  • Fork and send a pull request
  • Report issues

License & Acknowledgements

BSD style, see LICENSE file for details.


Boring tool to launch multiple afl-fuzz instances







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