"空格的魅力"

[root@expofrt1 logs]# /usr/bin/gzip -f /u01/IBM/HTTPServer/logs/access_log.`date -d yesterday+%Y%m%d`
date: invalid date `yesterday+%Y%m%d'
gzip: /u01/IBM/HTTPServer/logs/access_log.: No such file or directory
[root@expofrt1 logs]# date -d yesterday+%Y%m%d
date: invalid date `yesterday+%Y%m%d'
[root@expofrt1 logs]# bb=`date -d yesterday+%Y%m%d`
date: invalid date `yesterday+%Y%m%d'
[root@expofrt1 logs]#
[root@expofrt1 logs]#
[root@expofrt1 logs]# bb=`date -d yesterday +%Y%m%d`
[root@expofrt1 logs]# echo $bb
20090915