I'm writing a bash script that needs to delete old files.
It's currently implemented using :
find $LOCATION -name $REQUIRED_FILES -type f -mtime +1 -delete
This will delete of the files older than 1 day.
However, what if I need a finer resolution that 1 day, say like 6 hours old? Is there a nice clean way to do it, like there is using find and -mtime?
Does your find have the -mmin option? That can let you test the number of mins since last modification:
find $LOCATION -name $REQUIRED_FILES -type f -mmin +360 -delete
Or maybe look at using tmpwatch to do the same job. phjr also recommended tmpreaper in the comments.
You could to this trick: create a file 1 hour ago, and use the -newer file argument.
(Or use touch -t to create such a file).
If one's find does not have -mmin and if one also is stuck with a find that accepts only integer values for -mtime, then all is not necessarily lost if one considers that "older than" is similar to "not newer than".
If we were able to create a file that that has an mtime of our cut-off time, we can ask find to locate the files that are "not newer than" our reference file.
To create a file that has the correct time stamp is a bit involved because a system that doesn't have an adequate find probably also has a less-than-capable date command that could do things like: date +%Y%m%d%H%M%S -d "6 hours ago".
Fortunately, other old tools can manage this, albeit in a more unwieldy way.
To begin finding a way to delete files that are over six hours old, we first have to find the time that is six hours ago. Consider that six hours is 21600 seconds:
$ date && perl -e '@d=localtime time()-21600; \
printf "%4d%02d%02d%02d%02d.%02d\n", $d[5]+1900,$d[4]+1,$d[3],$d[2],$d[1],$d[0]'
> Thu Apr 16 04:50:57 CDT 2020
202004152250.57
Since the perl statement produces the date/time information we need, use it to create a reference file that is exactly six hours old:
$ date && touch -t `perl -e '@d=localtime time()-21600; \
printf "%4d%02d%02d%02d%02d.%02d\n", \
$d[5]+1900,$d[4]+1,$d[3],$d[2],$d[1],$d[0]'` ref_file && ls -l ref_file
Thu Apr 16 04:53:54 CDT 2020
-rw-rw-rw- 1 root sys 0 Apr 15 22:53 ref_file
Now that we have a reference file exactly six hours old, the "old UNIX" solution for "delete all files older than six hours" becomes something along the lines of:
$ find . -type f ! -newer ref_file -a ! -name ref_file -exec rm -f "{}" \;
It might also be a good idea to clean up our reference file...
$ rm -f ref_file