I am running Centos 7 kernel 3.10.0 on Oracle's VirtualBox 4.3.20 with an ext4 filesystem.
It seems that setting the "A" flag on a file doesn't keep the access time field from updating.
I created a file and used stat to check the access time -
touch ./foo
stat ./foo
which returns the following
File: ./foo
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: fd01h/64769d Inode: 1444417 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ user_1) Gid: ( 1000/ user_1)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2015-08-02 11:52:23.451524456 -0700
Modify: 2015-08-02 11:52:23.451524456 -0700
Change: 2015-08-02 11:52:23.451524456 -0700
Birth: -
If I then change the attribute and rerun stat -
sudo chattr +A ./foo
stat ./foo
I get the following which (I think) shows the access time value as updated?
File: ./foo
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: fd01h/64769d Inode: 1444417 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ user_1) Gid: ( 1000/ user_1)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2015-08-02 11:53:32.400974020 -0700
Modify: 2015-08-02 11:53:32.400974020 -0700
Change: 2015-08-02 11:53:32.400974020 -0700
Birth: -
Am I misunderstanding the use of the A flag? I thought it would keep the access time from changing?
Thanks for any insights you can offer. I am just trying to understand how things work.
Rog
+A will keep the same atime when you open the file with vi for example and not modify it. The result you've posted after modifying the attribute doesn't look right to me. Changing the attribute should only affect the 'Change' timestamp. In your case, all 3 timestamps are the same.
Related
I have some files on a scratch drive of a HPC server. The server automatically deletes files which are 2 weeks old.
Using stat filename.txt I can see the follow information. Is there a way to somehow open/touch/manipulate files to update the Access date to prevent deletion without actually changing the file?
File: ‘name’
Size: 2583438768 Blocks: 4819945 IO Block: 524288 regular file
Device: xxh/xxxd Inode: 10354xxxx Links: 1
Access: (/-rw-r--r--) Uid: (/) Gid: (/)
Context: system_u:object_r:tmp_t:s0
Access: 2022-11-22 09:47:33.000000000 -0800
Modify: 2019-12-06 06:50:33.000000000 -0800
Change: 2022-11-22 16:54:55.000000000 -0800
Birth: -
Use the Linux touch command, eg:
$ touch filename.txt
A symbolic link created by zfs is returning as ../../zd0, tested through multiple ways to check. Not sure why the result is not /dev/zd0 as that is the actual link as far as I am aware.
admin#r2-compute1:~$ ls -l /dev/zvol/cpool/cinder-volumes
lrwxrwxrwx 1 root root 9 Jun 25 09:53 /dev/zvol/cpool/cinder-volumes -> ../../zd0
admin#r2-compute1:~$ stat /dev/zvol/cpool/cinder-volumes
File: /dev/zvol/cpool/cinder-volumes -> ../../zd0
Size: 9 Blocks: 0 IO Block: 4096 symbolic link
Device: 6h/6d Inode: 640 Links: 1
Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2020-06-25 10:07:28.610707769 -0700
Modify: 2020-06-25 09:53:52.174435310 -0700
Change: 2020-06-25 09:53:52.174435310 -0700
Birth: -
admin#r2-compute1:~$ file /dev/zvol/cpool/cinder-volumes
/dev/zvol/cpool/cinder-volumes: symbolic link to ../../zd0
I am working with openstack and zfs and am wondering why the symbolic link returns "../../zd0" instead of "dev/zd0". I am not sure what the ../../ means and understanding would assist in my openstack implementation understanding. First time posting and Google and SymbolHound did not produce any results in regards to the meaning behind ../../
Thank you!
Probably while creating the soft links ../../zd0 was adopted instead of the full path /dev/zd0 (or whatever the path was supposed to be given).
If absolutely necessary, you may try to unlink this first and recreate the link by providing FULL-PATH to the DEVICE/FILE.
NOTE: Try this with caution and ensure the paths are correct, this is just the symbolic code to help you correct the error:
unlink /dev/zvol/cpool/cinder-volumes
ln -s /dev/zvol/cpool/cinder-volumes /dev/zd0
I read a name file, just the name and I need to print inode-number, the number of hard-links and others. How do I do that?
I thought initially to add the absolute path to my name file but I do not know how to that.
Use the stat command. Here is an example output:
UbuntuVBox:~/stackOver$ stat main.cpp
File: ‘main.cpp’
Size: 234 Blocks: 8 IO Block: 4096 regular file
Device: 801h/2049d Inode: 18749058 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ root) Gid: ( 1000/ root)
Access: 2016-06-01 10:02:55.858362281 +0100
Modify: 2016-06-01 10:02:48.770820244 +0100
Change: 2016-06-01 10:02:48.782826244 +0100
Birth: -
As you can see you get the inode number and number of links amongst other things.
I have a node application that is having it's STDOUT being redirected to a log file:
node app.js > /var/log/app.out
From inside my node program I want to reset the log in order to keep it from growing too large. I've attempted fs.truncate and fs.open('/var/log/app.out', 'w') in order to reset it's length, but when I try to verify the file size using ls or stat, the file size seems to quickly reset to 0, then reset to it's previous size plus new messages (I currently am forcing a lot of output).
root#ubuntu-1304-mike:/var/log# stat app.out
File: ‘app.out’
Size: 5885622 Blocks: 16 IO Block: 4096 regular file
Device: fc00h/64512d Inode: 270560 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-09-26 17:20:06.784564421 -0600
Modify: 2013-09-26 17:20:49.088565625 -0600
Change: 2013-09-26 17:20:49.088565625 -0600
Birth: -
root#ubuntu-1304-mike:/var/log# stat app.out
File: ‘app.out’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: fc00h/64512d Inode: 270560 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-09-26 17:20:06.784564421 -0600
Modify: 2013-09-26 17:20:51.772565702 -0600
Change: 2013-09-26 17:20:51.772565702 -0600
Birth: -
root#ubuntu-1304-mike:/var/log# stat app.out
File: ‘app.out’
Size: 6038458 Blocks: 16 IO Block: 4096 regular file
Device: fc00h/64512d Inode: 270560 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-09-26 17:20:06.784564421 -0600
Modify: 2013-09-26 17:20:53.640565755 -0600
Change: 2013-09-26 17:20:53.640565755 -0600
Birth: -
It seems that STDOUT is re-writing it's buffer to the file (regardless of how large the buffer is).
How can I truncate a file that STDOUT is actively being redirected to, without breaking out of my node app?
It seems that STDOUT is re-writing it's buffer to the file (regardless of how large the buffer is).
Nobody is re-writing a buffer, it's already written on the disk. When application finishes writing something, it remembers position where it finished, and it starts with this position later. It's not a node issue, and there's nothing you can do about it, it's how unix pipes work (unless there's some ugly hack to rewind a pipe I don't know about).
How can I truncate a file that STDOUT is actively being redirected to, without breaking out of my node app?
Don't use stdout redirection and write to a file instead. If you can't modify your app, write another app that uses more clever approach and redirect stdout to it like that: node app.js | node write-stdin-to-app.out.js
I just ran into this issue, as well. Using the append operator is the best way to solve it:
node app.js >> /var/log/app.out
Now you can truncate the file with fs.truncate or even:
echo -n > /var/log/app.out
Linux friends, how do you guys get a file timestamp in the resolution of milliseconds in Ubuntu? When I tried the command "stat" on my system, I get:
File: `tmp.dat'
Size: 14 Blocks: 8 IO Block: 4096 regular file
Device: 811h/2065d Inode: 13895454 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/ yqin) Gid: ( 1004/ dev)
Access: 2010-09-27 09:04:44.000000000 -0400
Modify: 2010-09-25 13:54:58.000000000 -0400
Change: 2010-09-25 13:54:58.000000000 -0400
It seems that the resolution is only up to second. Any ideas? Thanks a lot.
That depends on the filesystem. fat will give you 2 second resolution. ext2 and ext3 are based on seconds. ext4 has nanoseconds (http://www.softpanorama.org/Internals/Filesystems/linux_ext2_ext3.shtml, search for "minimum timestamp resolution").