ack outputs nothing using crontab in linux

ack outputs nothing using crontab in linux.

In the crontab file (edited with sudo crontab -e):

39 20 * * * /ext/test110.sh

And cat /ext/test110.sh will show

#! /bin/sh

/usr/bin/ack "localhost" /etc/hosts > /ext/1.t
which ack > /ext/2.t

After cron, there are 1.t and 2.t in /ext

cat 2.t will output /usr/bin/ack; However, nothing in 1.t.

If I run ack "localhost" /etc/hosts > /ext/3.t in bash (4.3.30) or sh directly, it will output: 127.0.0.1 localhost

It seems ack cannot work with cron. where is the bug? Thank you.

uname -a:

Linux xxx 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux

ack 2.14, Running under Perl 5.20.2 at /usr/bin/perl

Answer

/usr/bin/ack --nofilter "localhost" /etc/hosts > /ext/1.t works.