bug#26279: sort bug

[Ismael Cama]

Oh! Okay! I didn't know that '>' operator works like this. I didn't know
either "sponge" command. Thank you very much guys!

2017-03-28 18:06 GMT+02:00 Bishop Bettini <address@hidden>:

> On Tue, Mar 28, 2017 at 7:13 AM, Ismael Cama <address@hidden
>> >
>> wrote:
>>
>> > When you try to sort a file and write the result in the same file, all
>> the
>> > contents are deleted. Example:
>> >
>> > sort foo.txt > foo.txt
>> >
>>
> On Tue, Mar 28, 2017 at 9:30 AM, Michael Speer <address@hidden> wrote:
>
>> This isn't a bug in sort. The ">" redirection operator in your shell opens
>> and truncates the file to ready it for output before your shell invokes
>> sort. After sort starts running and opens and reads the foo.txt file, it
>> finds that empty file and outputs nothing, as you would expect if you had
>> purposely given an empty file to sort.
>>
>> You'll need to use a temporary file in order to avoid this.
>>
>> sort foo.txt > foo.txt.tmp ; mv foo.txt.tmp foo.txt
>
>
> One may also use sponge <https://linux.die.net/man/1/sponge>:
>
> sort foo.txt | sponge foo.txt
>
> Or an awkish equivalent, if one doesn't have moreutils:
>
> sponge ()
> {
>     awk '{a[NR] = $0} END {for (i = 1; i <= NR; i++) print a[i]}'
> }
>