Save lines to different files based on the date

Question

How can I force a re-evaluation of this each time?

cat > $(date '+%H-%M-%S').log

So that when I first output something it gets written to one file, and after a few seconds I make another ouput and it will be saved in a new file.

cat just symbolizes a always running program

Maybe you called it in the same second? Try adding `-%N` at the end. — choroba, Sep 03 '14 at 10:21
Yes, once. `cat` symbolizes a always running instance of any program. Which is not restarted. — Markus, Sep 03 '14 at 10:28
You want to change the output file for a running instance of `cat` - per se? — mikeserv, Sep 03 '14 at 10:33
Yes :) One instance which is always running that changes the output file for example at midnight. — Markus, Sep 03 '14 at 10:35

choroba · Accepted Answer · 2014-09-03T22:29:53.903

2

I replaced cat with a for loop that emits one line per second:

for ch in {a..e} ; do echo $ch ; sleep 1 ; done | \
while IFS= read -r line ; do printf '%s\n' "$line" >> $(date +%H-%M-%S) ; done

I used >> instead of > if more than one line comes in one second. You might need to add the month + day to not mix output from different days.

edited Sep 03 '14 at 22:29

answered Sep 03 '14 at 10:35

choroba

So can't be done with just bash? and where did my `cat` go? :) – Markus Sep 03 '14 at 10:37
I replaced `cat` with the `for` loop. – choroba Sep 03 '14 at 10:37
@Markus: OK, removed Perl. – choroba Sep 03 '14 at 10:39
Can you explain the edit? IFS= ? -r flag on read? printf instead of echo? thanks! – Markus Sep 04 '14 at 06:54
@Markus: Ask Gilles, he added those :-) Or read http://mywiki.wooledge.org/BashFAQ/001 and http://unix.stackexchange.com/q/65803/13792 – choroba Sep 04 '14 at 07:38

1 Answers1