How to combine two commands in -exec parameter of find? [duplicate]

Question

I have this find command to get all the files modified in the last 50 seconds which matchs with the following regex hell\d in the last 1000 characters. I use tail to get the last 1000 chars in order to speed up the search becouse the files to check are huge (3gb on average).

find /home/ouhma -newermt '50 seconds' -type f |
while read fic; do
    if tail -c 1000 "${fic}" | LANG=C LC_ALL=C grep -Pq 'hell\d'; then
        echo "${fic}"
    fi
done

It is posible to use -exec parameter to replace that ugly loop and to retrieve the result even faster?

This works, but I dont know if its the best way to do it:

find /home/ouhma -newermt '50 seconds' -type f -exec bash -c 'LANG=C LC_ALL=C grep -Pq "hell\d" <(tail -c 1000 "{}") && echo "{}"' \;

heemayl · Accepted Answer · 2016-10-20 10:51:25Z

3

Multiple -exec actions can follow one another, one -exec will be run if the previous -exec succeeds i.e. the command run by -exec returns exit status 0.

Do:

find /home/ouhma -type f -newermt '50 seconds' -exec env LC_ALL=C \
       bash -c 'grep -Pq "hell\d" <(tail -c 1000 "$1")' _ {} \; -exec echo {} \;

As you are just printing the filename, this would suffice though:

find /home/ouhma -type f -newermt '50 seconds' -exec env LC_ALL=C \
       bash -c 'grep -Pq "hell\d" <(tail -c 1000 "$1") && echo "$1"' _ {} \;

edited Oct 20, 2016 at 10:51

answered Oct 20, 2016 at 8:24

heemayl

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9 Comments

mllamazares Over a year ago

If I test your command by this way: find /home/ouhma/hello.txt -exec LC_ALL=C grep -Pq 'hell\d' <(tail -c 1000 {}) \; -exec echo {} \; It returns the following error: tail: cannot open '{}' for reading: No such file or directory find: 'LC_ALL=C': No such file or directory

anubhava Over a year ago

Spawning a bash for every file won't be faster than OP's own attempt.

heemayl Over a year ago

@anubhava True, check now.

anubhava Over a year ago

Good but now it will scan full 3GB data not just last 1000 characters.

heemayl Over a year ago

@anubhava Hmmm..chicken-egg problem i see :/

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