how can I lock my keyboard while I'm away from the computer without using lock command. What other commands gives me the option to lock keyboard device?
thanks (7 Replies)
When I want to use the editor ,whether vi or textedit,it prompts for entering a key. How can I disable this function?many thanks for offering solutions! (1 Reply)
I only able to lock user ID with passwd -l username
It seems there is no option for me to unlock ID in solaris?
Is there any command as below?
passwd -u username
Appreciate someome can share with me the way to do it. (1 Reply)
When I do HMC upgrade, I download HMC code from IBM web site and burn it to a DVD disk, when I get the first DVD out of HMC's dvd rom and input the second DVD, it shows error:
The requested device is already locked by the process: Install Corrective Service.
Would you like to try to request a... (2 Replies)
We have two processes, one which copies a control file into a folder and another which is polling this folder and reading the control files.
Sometimes they clash and the reader fails because the copy is still happening.
We have been told that we should change the copy to a move because the... (1 Reply)
Hello all,
If anyone has time, I have a few questions:
How do I do the following in Linux. We are using Red Hat and Oracle Enterprise Linux, which is based on Red Hat too.
1. How to lock the account after a few (like 3) invalid password attempts?
2. How do you lock a screen after 30... (1 Reply)
Hi all,
I have to test some user priviliges. The goal is to be sure that an unauthorized user can't restart some modules (ssh, mysql etc...).
I'm trying to automate it with a shell script but in same cases I got the syslog broadcast message.
Is there any way to simply get a return code... (3 Replies)
Requirement:First i need to unlock the directory which i had a script for it.If i select app1 it should unlock the directory and after chnages in the script once need to lock the directory with lock command
The below highlighed variables in lock and unlock has to be changed according... (2 Replies)
I use Debian default encryption disk encryption. Only /boot it's not encrypted. When I boot I need to type my password, and then I will be logged in. But now I can't login. It always says that I typed the wrong password, but I typed the correct password.
I tried to boot in live-CD and try unlock... (3 Replies)
Discussion started by: zognadal
3 Replies
LEARN ABOUT CENTOS
flock
FLOCK(2) Linux Programmer's Manual FLOCK(2)NAME
flock - apply or remove an advisory lock on an open file
SYNOPSIS
#include <sys/file.h>
int flock(int fd, int operation);
DESCRIPTION
Apply or remove an advisory lock on the open file specified by fd. The argument operation is one of the following:
LOCK_SH Place a shared lock. More than one process may hold a shared lock for a given file at a given time.
LOCK_EX Place an exclusive lock. Only one process may hold an exclusive lock for a given file at a given time.
LOCK_UN Remove an existing lock held by this process.
A call to flock() may block if an incompatible lock is held by another process. To make a nonblocking request, include LOCK_NB (by ORing)
with any of the above operations.
A single file may not simultaneously have both shared and exclusive locks.
Locks created by flock() are associated with an open file table entry. This means that duplicate file descriptors (created by, for exam-
ple, fork(2) or dup(2)) refer to the same lock, and this lock may be modified or released using any of these descriptors. Furthermore, the
lock is released either by an explicit LOCK_UN operation on any of these duplicate descriptors, or when all such descriptors have been
closed.
If a process uses open(2) (or similar) to obtain more than one descriptor for the same file, these descriptors are treated independently by
flock(). An attempt to lock the file using one of these file descriptors may be denied by a lock that the calling process has already
placed via another descriptor.
A process may hold only one type of lock (shared or exclusive) on a file. Subsequent flock() calls on an already locked file will convert
an existing lock to the new lock mode.
Locks created by flock() are preserved across an execve(2).
A shared or exclusive lock can be placed on a file regardless of the mode in which the file was opened.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EBADF fd is not an open file descriptor.
EINTR While waiting to acquire a lock, the call was interrupted by delivery of a signal caught by a handler; see signal(7).
EINVAL operation is invalid.
ENOLCK The kernel ran out of memory for allocating lock records.
EWOULDBLOCK
The file is locked and the LOCK_NB flag was selected.
CONFORMING TO
4.4BSD (the flock() call first appeared in 4.2BSD). A version of flock(), possibly implemented in terms of fcntl(2), appears on most UNIX
systems.
NOTES
flock() does not lock files over NFS. Use fcntl(2) instead: that does work over NFS, given a sufficiently recent version of Linux and a
server which supports locking.
Since kernel 2.0, flock() is implemented as a system call in its own right rather than being emulated in the GNU C library as a call to
fcntl(2). This yields true BSD semantics: there is no interaction between the types of lock placed by flock() and fcntl(2), and flock()
does not detect deadlock.
flock() places advisory locks only; given suitable permissions on a file, a process is free to ignore the use of flock() and perform I/O on
the file.
flock() and fcntl(2) locks have different semantics with respect to forked processes and dup(2). On systems that implement flock() using
fcntl(2), the semantics of flock() will be different from those described in this manual page.
Converting a lock (shared to exclusive, or vice versa) is not guaranteed to be atomic: the existing lock is first removed, and then a new
lock is established. Between these two steps, a pending lock request by another process may be granted, with the result that the conver-
sion either blocks, or fails if LOCK_NB was specified. (This is the original BSD behavior, and occurs on many other implementations.)
SEE ALSO flock(1), close(2), dup(2), execve(2), fcntl(2), fork(2), open(2), lockf(3)
Documentation/filesystem/locks.txt in the Linux kernel source tree (Documentation/locks.txt in older kernels)
COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2013-02-11 FLOCK(2)