Binary "tail" a file

Question

I would guess most people on this site are familiar with tail, if not - it provides a "follow" mode that as text is appended to the file tail will dump those characters out to the terminal.

What I am looking for (and possibly to write myself if necessary) is a version of tail that works on binary files. Basically I have a wireless link that I would like to trickle a file across as it comes down from another network link. Looking over the tail source code it wouldn't be too hard to rewrite, but I would rather not reinvent the wheel! This wouldn't strictly be "tail" as I would like the entire file to be copied, but it would watch as new bytes were added and stream those.

Ideas?

Answer 1

Pipe it to hexdump:

tail -f somefile | hexdump -C

Answer 2

There is also the bintail application which appears to be more robust than the aforementioned script.

The bintail package contains a single application, bintail. The program reads a normal file from disk, and pipes the output to stdout, byte-by-byte, with no translation, similar to what tail(1) does to text files. This is useful for "tailing" binary files, such as WAV files, while they are being written in realtime. This app is a work in progress, but it already does what it was designed to do for me.

Answer 3

Linux coreutils tail(1) works just fine on binary files. For most applications, you just need to avoid its line-orientation, so that the output doesn't begin in some random spot in the middle of a data structure. You can do that by simply starting at the beginning of file, which is also exactly what you asked for:

tail -c +1 -f somefile

works just fine.

Answer 4

This hastily coded Python script for Windows may be of assistance:

# bintail.py -- reads a binary file, writes initial contents to stdout,
# and writes new data to stdout as it is appended to the file.

import time
import sys
import os
import msvcrt
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)

# Time to sleep between file polling (seconds)
sleep_int = 1

def main():
    # File is the first argument given to the script (bintail.py file)
    binfile = sys.argv[1]

    # Get the initial size of file
    fsize = os.stat(binfile).st_size

    # Read entire binary file
    h_file = open(binfile, 'rb')
    h_bytes = h_file.read(128)
    while h_bytes:
        sys.stdout.write(h_bytes)
        h_bytes = h_file.read(128)
    h_file.close()


    # Loop forever, checking for new content and writing new content to stdout
    while 1:
        current_fsize = os.stat(binfile).st_size
        if current_fsize > fsize:
            h_file = open(binfile, 'rb')
            h_file.seek(fsize)
            h_bytes = h_file.read(128)
            while h_bytes:
                sys.stdout.write(h_bytes)
                h_bytes = h_file.read(128)
            h_file.close()
            fsize = current_fsize
        time.sleep(sleep_int)

if __name__ == '__main__':
    if len(sys.argv) == 2:
        main()
    else:
        sys.stdout.write("No file specified.")