linux - Why does bash short curcuit fail in crontab? -


if in terminal do

[ $(/usr/bin/date +"%y%m%d") -le 20171209 ] && echo aaa >> /tmp/a

it works. if in crontab -e

* * * * *   echo aaa >> /tmp/a

then works. if in crontab -e

* * * * *   [ $(/usr/bin/date +"%y%m%d") -le 20171209 ] && echo aaa >> /tmp/a

then nothing happens.

looking @ /var/log/cron see

sep 12 08:36:01 enote crond[8809]: (root) cmd ([ $(/usr/bin/date +")

question

can explain issue is?

percent sign has special meaning in crontab, must escaped \%

man 5 crontab /percent

percent-signs (%) in command, unless escaped backslash (\), changed newline characters, , data after first % sent command  standard input.

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