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#! /usr/bin/env lua
local M = require 'posix.fcntl'
local S = require 'posix.sys.stat'
local fd = M.open(
'file.txt',
M.O_CREAT + M.O_WRONLY + M.O_TRUNC,
S.S_IRUSR + S.S_IWUSR + S.S_IRGRP + S.S_IROTH
)
-- Set lock on file
local lock = {
l_type = M.F_WRLCK; -- Exclusive lock
l_whence = M.SEEK_SET; -- Relative to beginning of file
l_start = 0; -- Start from 1st byte
l_len = 0; -- Lock whole file
}
if M.fcntl(fd, M.F_SETLK, lock) == -1 then
error('file locked by another process')
end
-- Do something with file while it's locked
require 'posix.unistd'.write(fd, 'Lorem ipsum\n')
-- Release the lock
lock.l_type = M.F_UNLCK
M.fcntl(fd, M.F_SETLK, lock)
|
