Why do I get the information of “suspended (tty input)” when I run my script in the background

问题

I've written a tcsh script to clear garbage data in a cluster, the code is :

set hosts = $1
set clear_path = $2
foreach i ($hosts)
    rsh $i rm -rvf $clear_path
end

When I run this script in the background like this :

disk_clean.sh hosts_all /u0/data/tmp > log &

The job will get stuck and show the information like this:

[1] + Suspended (tty input)

If I run this in foreground, it can finish normally. Why does this happen? How can I run this script in the background and redirect the output into a log file?

来源：https://stackoverflow.com/questions/42361200/why-do-i-get-the-information-of-suspended-tty-input-when-i-run-my-script-in