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Tag: filesystems
Polling for readiness file
I work on Linux. How to know that a gzip file is ready? I have a server that polls files in directory /dir/. There is an another, independent process that gzip files to /dir/. How can my server know that file is ready? Answer There is no ready-made solution for this. Looking at the last modification timestamp…
how to choose chunk size when reading a large file?
I know that reading a file with chunk size that is multiple of filesystem block size is better. 1) Why is that the case? I mean lets say block size is 8kb and I read 9kb. This means that it has to go and get 12kb and then get rid of the other extra 3kb. Yes it did go and
Is running `sync` necessary after writing a disk image?
Common way to write an image to disk looks like: After this command, is it necessary to run sync? sync(2) explains it only flushes filesystem caches. Since dd command is not related to any filesystem, I think it is not necessary to run sync. However, block layer is complex and in doubt, most people prefers to…
Recursively re-spawn file on fsnotify Remove/Rename (Golang)
The Goal: I am attempting to monitor a file that is subject to being moved or deleted at any time. If and when it is, I’d like to re-generate this file so that an app can continue to write to it. Attempted: I have attempted to do this by implementing two functions, monitorFile() to listen for fsnotify e…
Get filesystem creation date in C
I need to know the creation datetime of the filesystem on a disk (in a Linux machine) with C. I would like to avoid using shell commands, such as and make a parser. Thanks Answer From a program coded in C (or in any language capable of calling C routines) you would use the stat(2) system call (or, with recent
Running out of space on Linux, copying 12GB of files to a 15GB file system
I have two virtual Linux servers, one for development and one in production, a typical setup one would expect. On the development server I have files that I need to copy to the production server, that amount to 12GB, well according to the “du -h” command. The production server has 15GB free, accor…
Deleting files after 7 days not working
I am trying to delete all files that are older than 7 days. The command is working but not correctly. It does delete files but it’s not accurate. The find does delete files, but when I run the ls command does contain files that should be deleted. For example today is November 7th. The find should delete…
The optimal way to lock and write to a file in Scala on Linux
I’m having a hard time finding the correct way to do any advanced file-system operations on Linux using Scala. The one which I really can’t figure out if best described by the following pseudo-code: Basically open a file in append mode (create it if it’s non existent), get an exclusive lock …
where is the __init function of ext4?
As every module that is to be inserted in the kernel needs an __init function. where can I find the __init function of the original ext4 module written by linus torvalds? I want to make some changes in it. Answer I suppose you’re looking for this method : https://github.com/torvalds/linux/blob/master/fs…