tag 25475 notabug
close 25475
stop
On 01/19/2017 12:44 AM, f0rhum wrote:
> deleted (then sed -i '$ d' $LOGF;), then immediately 3 + 43 printed
________________^^^^^^^^^^^^^^^^^^
That's the reason: "sed -i" opens a new, temporary file and filters the
original content from 'file' to the new one; finally, it renames the
temporary file to the original file name:
$ strace -e open,read,write,rename sed -i '$ d' file
...
open("file", O_RDONLY) = 3
open("./sedLPtf2x", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
read(3, "xxx\n"..., 4096) = 953
write(4, "xxx\n", 4) = 4
...
read(3, "", 4096) = 0
read(3, "", 4096) = 0
rename("./sedLPtf2x", "file") = 0
+++ exited with 0 +++
The file has the same name, but the file descriptor that tail opened
at startup is a different one. You can also see that the inode number
of the file changes:
$ ls -logi file
5770837 -rw-r--r-- 1 817 Jan 19 00:54 file
$ sed -i '$ d' file
$ ls -logi file
5774048 -rw-r--r-- 1 751 Jan 19 01:00 file
As "tail -f" means to follow the original file descriptor, it is
not supposed to follow the new file (which has the same name):
-f, --follow[={name|descriptor}]
output appended data as the file grows;
an absent option argument means 'descriptor'
As such, there is no bug in tail; therefore I'm marking it as such,
and close this issue in our bug tracker.
Have a nice day,
Berny
