progbar.py : Print current position in file versus file length.

progbar.py

#!/bin/env python
import sys, os

USAGE="""
	./progbar.py PROCESS_ID [FILE_DESCRIPTOR_NUMBER]
	
	Usage:
	
	  ./progbar.py PROCESS_ID
	
	    Prints all file descriptor numbers along with the path of
	    each.
	
	  ./progbar.py PROCESS_ID FILE_DESCRIPTOR_NUMBER
	
	    Prints the current seek location of the process in the
	    file, the total length of the file, and the current
	    location versus the end as a percentage.
	
"""

def print_file_descriptors(pid):
    fd_dir = os.path.join('/proc', pid, 'fd')
    fds = os.listdir(fd_dir)
    for fd in fds:
        print fd, "=>", os.readlink(os.path.join(fd_dir, fd))

def print_current_position(pid, fd):
    # step 1: get current location
    fdinfo_filename = os.path.join('/proc', pid, 'fdinfo', fd)
    fdinfo_handle = file(fdinfo_filename)
    location = int(fdinfo_handle.readlines()[0].split()[1])
    fdinfo_handle.close()

    # step 2: get total size.
    file_path = os.readlink(os.path.join('/proc', pid, 'fd', fd))
    size = os.stat(file_path).st_size

    # report
    print location, "/", size
    print "%.2f%%" % (float(location)/float(size)*100)

def main():
    if len(sys.argv) == 2:
        # Case 1: Print all file descriptor numbers and filenames.
        pid = sys.argv[1]
        print_file_descriptors(pid)

    elif len(sys.argv) == 3:
        # Case 2: Print the location of the file pointer, this file size,
        # and the percentage of the file behind the file pointer.

        pid = sys.argv[1]
        fd = sys.argv[2]
        print_current_position(pid, fd)

    else:
        # Case 3: Print usage and exit
        print USAGE


if __name__ == "__main__":
    main()