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@amitsaha
Last active Mar 13, 2022
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Simple implementation of the tail command in Python
'''
Basic tail command implementation
Usage:
tail.py filename numlines
'''
import sys
import linecache
if len(sys.argv) !=3:
print 'Usage: tail.py <file> <nlines>'
sys.exit(1)
# filename and number of lines requested
fname, nlines = sys.argv[1:]
nlines = int(nlines)
# count the total number of lines
tot_lines = len(open(fname).readlines())
# use line cache module to read the lines
for i in range(tot_lines - nlines + 1, tot_lines+1):
print linecache.getline(sys.argv[1],i),
""" This is a more efficient version, since it does not read the entire
file
"""
import sys
import os
bufsize = 8192
lines = int(sys.argv[1])
fname = sys.argv[2]
fsize = os.stat(fname).st_size
iter = 0
with open(sys.argv[2]) as f:
if bufsize > fsize:
bufsize = fsize-1
data = []
while True:
iter +=1
f.seek(fsize-bufsize*iter)
data.extend(f.readlines())
if len(data) >= lines or f.tell() == 0:
print(''.join(data[-lines:]))
break
@blasti
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blasti commented Mar 13, 2022

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