Questions tagged [concurrency]

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10
votes
1answer
173 views

Moving a file to a file that is being read

When a file is moved and the destination file already exists and is currently being read, will the operation succeed? Will it depend on how long the reading operation on the destination file lasts?
2
votes
1answer
835 views

2 or more programs in same USB serial converter

Having a network of lets say 10 devices in RS-485, connected to the linux PC with a RS-485 to USB Converter. Already there is a C program interacting with the serial converter at /dev/ttyUSB0. My ...
19
votes
1answer
12k views

Is using rsync while source is being updated safe?

Is it safe to use rsync when the source filesystem is mounted and writeable, assuming that it may very well be modified while rsync is running? I presume that under race conditions I may not get the ...
4
votes
1answer
131 views

Edge cases in filesystem operations during backup and file copy

I have a question about file access in Linux that I cannot sum it up completely. Consider that I have a home directory that I backup it using rsync triggered via cron. My home directory is on an EXT4 ...
5
votes
1answer
3k views

What's the use dirsync option for mount?

Today I stumbled upon this mount's option: dirsync All directory updates within the filesystem should be done synchronously. This affects the following system calls: creat, link, unlink, ...
16
votes
3answers
8k views

tee + cat: use an output several times and then concatenate results

If I call some command, for instance an echo I can use the results from that command in several other commands with tee. Example: echo "Hello world!" | tee >(command1) >(command2) >(command3)...
1
vote
1answer
140 views

Will files created under source directory after running `cp` be copied?

Suppose I use cp to copy a directory to another place. If the process takes long, and I create a new file under the source directory, will it be copied, or does it depend on something?
1
vote
0answers
2k views

“No PostgreSQL user name specified” - possible concurrency issues?

For my dissertation I'm running the same cronjob on around 300 machines, which is: 10,25,40,55 * * * * /path/to/db_script.sh 1>/dev/null This script gets some values from the system (whether ...
1
vote
1answer
3k views

Capture user input while doing other things

Is there a way to have the output of a subprocess (something other than 'sleep' below) be dovetailed with the output from a foreground command-loop? For example: while true do echo "updating ...
32
votes
4answers
36k views

How to launch a set of program inside tmux or gnome-terminal within a script?

I wanted to launch a few commands simultaneously in tmux or gnome-terminal or xfterminal , every different tab with a single command running , and close that tab when that command finishes. Any ...
7
votes
2answers
20k views

How do you make a cross-process locking in Linux (C/C++)?

I need to make sure one process executes only in one instance at a time. On Windows you could use named mutex. But I have no idea what to use on Linux. I think I've seen an approach were app creates ...
4
votes
2answers
2k views

rm -rf failing if deleting in parallel

rm -rf will fail if something tries to delete the same file tree (I think because rm enumerates the files first, then deletes). A simple test: # Terminal 1 for i in `seq 1 1000`; do mkdir -p /tmp/...
5
votes
2answers
3k views

Can there be multiple kernels executing at the same time?

I know that Linux OS's are typically multi-programmed, which means that multiple processes can be active at the same time. Can there be multiple kernels executing at the same time?