I'm using Ubuntu 14.04 dev with tar 1.26+dfsg-8 and sometimes I'm seeing the message "tar: .: file changed as we read it" which seems to not be true. This bugs seems to be very difficult to reproduce and even the reproducing behavior is really annoying. As I got today on testing the chance for easy reproducing I have made a look with inotifywait what is happening:
sworddragon@ubuntu:~$ mkdir tmp
sworddragon@ubuntu:~$ inotifywait -mr tmp &
[1] 12445
sworddragon@ubuntu:~$ Setting up watches. Beware: since -r was given, this may take a while!
Watches established.
^C
sworddragon@ubuntu:~$ cd tmp
sworddragon@ubuntu:~/tmp$ tar --exclude "*\.tar" -zcf test.tar .
tmp/ OPEN,ISDIR
tmp/ CREATE test.tar
tmp/ OPEN test.tar
tar: .: file changed as we read it
tmp/ CLOSE_NOWRITE,CLOSE,ISDIR
tmp/ MODIFY test.tar
tmp/ CLOSE_WRITE,CLOSE test.tar
sworddragon@ubuntu:~/tmp$ rm test.tar
tmp/ DELETE test.tar
sworddragon@ubuntu:~/tmp$ tar --exclude "*\.tar" -cf test.tar .
tmp/ CREATE test.tar
tmp/ OPEN test.tar
tmp/ OPEN,ISDIR
tmp/ CLOSE_NOWRITE,CLOSE,ISDIR
tmp/ MODIFY test.tar
tmp/ CLOSE_WRITE,CLOSE test.tar
sworddragon@ubuntu:~/tmp$ rm test.tar
tmp/ DELETE test.tar
sworddragon@ubuntu:~/tmp$ tar --exclude "*\.tar" -zcf test.tar .
tmp/ OPEN,ISDIR
tmp/ CREATE test.tar
tmp/ OPEN test.tar
tar: .: file changed as we read it
tmp/ CLOSE_NOWRITE,CLOSE,ISDIR
tmp/ MODIFY test.tar
tmp/ CLOSE_WRITE,CLOSE test.tar
sworddragon@ubuntu:~/tmp$ tar --exclude "*\.tar" -zcf test.tar .
tmp/ OPEN,ISDIR
tmp/ MODIFY test.tar
tmp/ OPEN test.tar
tmp/ CLOSE_NOWRITE,CLOSE,ISDIR
tmp/ MODIFY test.tar
tmp/ CLOSE_WRITE,CLOSE test.tar
The bug only appears if a compression is activated (even with -J) and the tar archive doesn't already exist (tested both multiple times). The curious is if I'm closing the terminal and open it again I'm not able to reproduce this anymore. The bug will then randomly appear whenever I'm using tar.
I have the same problem with tar version 1.27.1 on ubuntu server 14.04.1. Error "tar: .: file changed as we read it" and no files are being changed.
I made this research:
If I repeat the tar operation the errors appear on the same files.
I deleted a folder with some error files and then the error appeared in other files. If I repeat the operation then the errors keep on the same new files.
After undeleting the recently deleted folder then the errors come back to the initial group of files.
Each day, as the users work on their files (this is a backup procedure) the error files chage, but if I repeat the tar procedure the same night (without source file changes) the error remains in the same files.
It seems to be a random error affected by the files and folders being "tarred", but I couldn't find a failure pattern.