[TUHS] sh: cmd | >file

[Michael Parson]

On 2020-01-03 13:44, Warner Losh wrote:
> On Fri, Jan 3, 2020, 1:39 PM markus schnalke <meillo at marmaro.de> wrote:
> 
>> Hoi.
>> 
>> [2020-01-03 13:45] markus schnalke <meillo at marmaro.de>
>> >
>> > I'd be interested in any stories and information around this
>> > topic.
>> 
>> Especially I'd like to know since when and why ``>file'' is a
>> full command? Was it clever design or by accident?
> 
> 
> It's used to open files in shell scripts. Iirc, exec >foo 5>& and the
> like...

I've also used it to truncate files:

$ dd if=/dev/zero of=file count=10
10+0 records in
10+0 records out
5120 bytes (5.1 kB, 5.0 KiB) copied, 0.000686599 s, 7.5 MB/s

$ ls -l file
-rw-rw-r-- 1 mparson mparson 5120 Jan  3 16:45 file

$ >file

$ ls -l file
-rw-rw-r-- 1 mparson mparson 0 Jan  3 16:46 file

A more likely use case is to truncate a log file then HUP syslogd.

-- 
Michael Parson
Pflugerville, TX
KF5LGQ