‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Thursday, May 16, 2019 10:57 PM, Chet Ramey <chet.ra...@case.edu> wrote:
> On 5/16/19 4:25 PM, howaboutsyne...@protonmail.com wrote:
>
> > Hi. Would bash devs even consider replacing the current behaviour of ">"
> > (redirection) to do the equivalent of the following(under the hood) ?
>
> I doubt it. That's not how it's defined to behave, and there's no good
> reason to do it.
Thanks. On second thought, there's a reason bash devs should not do it:
O_APPEND may lead to corrupted files on NFS filesystems if more than one
process appends data to a file at once. This is because NFS does not support
appending to a file, so the client kernel has to simulate it, which can't
be done without a race condition.
- from `man 2 open`
>
> > When:
> > `command > $somewhere`
> > then actually do(under the hood):
> > : > $somewhere
> > command >> $somewhere
> > ie. create&truncate file, then open it in append mode and redirect to it,
> > instead of what it currently does(aka not append).
>
> Why not just use the version you supply above in the cases where it
> matters?
I'm indeed doing that for /usr/share/automake-1.16/test-driver,
but I was hoping to future proof it for unknown situations.
To answer my own question:
> If not, could the devs(or anyone) please suggest a place in the source code
> where to look for attempting to implement/change this for myself?
in ./make_cmd.c function `make_redirection`, code:
case r_output_direction: /* >foo */
case r_output_force: /* >| foo */
case r_err_and_out: /* &>filename */
temp->flags = O_TRUNC | O_WRONLY | O_CREAT;
break;
Addind O_APPEND there didn't immediately hurt,
and ./redir.c function `do_redirection_internal`
something there...
I'll try some things.
>
> -------------------------------------------------------------------------------
>
> `The lyf so short, the craft so long to lerne.'' - Chaucer`Ars longa, vita
> brevis'' - Hippocrates
> Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
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