fftest

Open fftest on an event

$ fftest [/dev/input/eventX]

fftest [options]

-h
    Display help and exit

-v
    Increase verbosity of output

-f
    Specify test file path

-n
    Number of test iterations

fftest is not a standard Linux command included in major distributions such as Ubuntu, Fedora, or Arch. It appears in specialized testing suites like the Linux Test Project (LTP), specifically within the syscalls/fcntl test cases. fftest (or variants like fftest01, fftest02) is used to validate file control operations, particularly fcntl() flags such as F_SETFL for non-blocking I/O, close-on-exec, and file status flags on POSIX systems.

It exercises kernel behavior for file descriptors, ensuring compliance with standards like SUSv3/POSIX. Typically run in a test harness like ltp-pan, it creates files, sets flags, performs I/O operations, and checks for expected errno values or flag persistence across forks/execs. Not intended for general user use; primarily for developers and QA testing file system and libc implementations.

Usage requires installing LTP (e.g., via ltp-full package or building from source at linux-test-project.org). Run individually as ./fftest in the LTP runtests directory for debugging kernel regressions.

Install via yum install ltp-full or apt install ltp-full; build from git://git.kernel.org/pub/scm/linux/kernel/git/ltp/ltp.git

./runtest fftest01
./fftest -v -f /tmp/testfile