类似shell中grep、more、less

mysql> pager less
PAGER set to 'less'

mysql> pager
Default pager wasn't set, using stdout.

mysql>
PAGER set to stdout

mysql> pager cat > /dev/null
PAGER set to 'cat > /dev/null'

mysql> pager md5sum
PAGER set to 'md5sum'

mysql> pager grep Sleep | wc -l
PAGER set to 'grep Sleep | wc -l'