Questions tagged [flock]
The flock tag has no summary.
31 questions
0
votes
1
answer
71
views
flock not working between forks on the same fd
I am working on a process that forks several times. To debug it, I am using a debug file for which I open a fd and which stays the same for all child forks. Then I have a function print_debug, that ...
- 25
2
votes
1
answer
100
views
How to share a writable flock file in /tmp/ between two users?
It seems that Linux has tightened up security in /tmp in later kernels than 3.x and if /tmp has the sticky bit set another user may not modify a 0777 file.
Are there any work arounds for sharing a ...
- 852
-1
votes
1
answer
2k
views
What does "trap: SIGINT: bad trap" mean and how do I fix it?
I moved code to a new virtual server running Ubuntu 22.
I have the following (edited to make names shorter) in my crontab so that it runs myCommand only if it is not already running:
*/1 * * * * ...
- 3
2
votes
1
answer
302
views
When I use flock it exits immediately instead of waiting
I was confused for a very long time with the meaning of the -n flag for flock(1).
Basically there are many guides for this tool, and often what we see is some command like flock -n 100. Here, fd ...
- 2,432
2
votes
1
answer
120
views
Flock and bash strange chicken and egg problem
In which order are the distinct steps of this bash command done:
(flock -n 9) 9> toto.txt
If I do only the subshell part:
(flock -n 9)
I get this result:
flock: 9: Mauvais descripteur de fichier (...
- 137
0
votes
0
answers
228
views
Force running a script using flock?
If given a lock on a script using flock(), is it possible to make a force run/unlock based on some argument passed to the script?
1
vote
0
answers
214
views
Ubuntu user not affected by sticky bit on Ubuntu 22.04
I experience a strange behaviour in stick bit on /tmp directory and flock command. Tried with two cases:
Case 1: create file with Ubuntu user, root have no access to the created file.
ubuntu@:~$ touch ...
- 131
0
votes
2
answers
128
views
Shared locking of scripts that may call each other
This is unusual problem and probably it is the consequence of bad design. If somebody can suggest anything better, I'd happy to hear. But right now I want to solve it "as is".
There is a ...
- 1,779
0
votes
1
answer
1k
views
Testing file locking
I have a script which locks a file to avoid concurrent access to it, How can I execute this same script from two different terminals synchronously, to check if it works?
Here is the script
#!/bin/bash
...
- 101
-2
votes
1
answer
347
views
Are there any plans for Linux to add higher-level things like Windows' WaitForMultipleObjects?
WaitForMultipleObjects is one of several Windows kernel functions that can suspend and synchronize a calling thread with other threads until resources or etc are available, similar to flock in Linux, ...
0
votes
1
answer
288
views
Synchronizing access to shared, remote resource
I have a shared cache on a remote server that multiple clients are reading and writing to, so I need to synchronize access to this cache. I imagine I could:
SSH into the remote and acquire a flock on ...
- 101
0
votes
2
answers
206
views
How to run eval with lockf command?
I have a command which I run via eval as shown below.
#! /bin/sh
readonly scr="MYENV=1 sh /tmp/scr.sh"
eval ${scr} -a 1 -b 2
Now I want to run the scr script with lockf utility, so I made ...
- 235
1
vote
0
answers
490
views
Is this flock usage with if-else safe?
I have two shell scripts that may be run in parallel but may also be run one at a time. Both scripts rely on an initial setup step that takes a while and can't be run by both at the same time.
To ...
- 227
-2
votes
2
answers
2k
views
is there a really simple and reliable way to create a unique lock (file) on linux? without using `flock` [closed]
EDIT: I learned how to use flock for exclusive lock and how to not mess with it: https://superuser.com/questions/1619940/flock-is-randomly-failing-on-desktop-pc-but-not-on-notebook-could-be-defectiv/. ...
- 4,557
13
votes
3
answers
11k
views
Handling of stale file locks in Linux and robust usage of flock
I have a script I execute via cron regularly (every few minutes). However the script should not run multiple times in parallel and it sometimes runs a bit longer, thus I wanted to implement some ...
- 171