一个小标点引发一串匪夷所思的问题........ - Chinaunix

while IFS=: read -r f1 f2 f3 f4 f5 f6 f7 f8
do
if [ ! -z $f8 ]
then
expd="`date -d "1970-01-01+$f8 day" '+%Y-%m-%d'`"
echo -e "$ATT The account: $f1 will expried at $expd. Please contact your administrator!"
else echo -e "Checking account $f1 expire date. $OK"
fi
done</etc/shadow

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[root@butter ~]# ./secure.sh
........
Checking account gopher expire date. [ OK ]
***Attention*** The account: john will expried at 2013-03-04. Please contact your administrator!
Checking account nobody expire date. [ OK ]
.....
[root@butter ~]# cat /etc/shadow|grep john
john:$6$hX2SaZv8$TZbICUPboyu2XmVVgYOfDFqvR7sKJeD0N5D2pvmxo3H8bmVl8eCroOLcJYEw6.uvkfQwgg/8b2wV1dvszi79a.:15708:0:99999:7::15768:

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[root@butter ~]# cat secure.sh
while IFS=: read -r f1 f2 f3 f4 f5 f6 f7 f8
do
echo $f2
done</etc/shadow
[root@butter ~]# ./secure.sh
$2y$10$ULX4kt.sVMbsjg0bBwj8FuCF9Exy2GzxnpgbCOZLf.Jtj5FQ7.DjC
ALL_LINE Desktop Documents FLAG UNIQ_LINE autoinst.xml bin inst-sys passwd passwd2 secure.sh st
ALL_LINE Desktop Documents FLAG UNIQ_LINE autoinst.xml bin inst-sys passwd passwd2 secure.sh st
ALL_LINE Desktop Documents FLAG UNIQ_LINE autoinst.xml bin inst-sys passwd passwd2 secure.sh st
ALL_LINE Desktop Documents FLAG UNIQ_LINE autoinst.xml bin inst-sys passwd passwd2 secure.sh st
.............

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[root@butter ~]# cat secure.sh
while IFS=: read -r f1 f2 f3 f4 f5 f6 f7 f8
do
if [ -z "$f2" ]
then
echo -e "$WAR The account: $f1 has empty password! Please contact your administrator!"
else echo -e "Checking the account $1 has set a password $OK"
fi
done</etc/shadow
[root@butter ~]# ./secure.sh
Checking the account root has set a password [ OK ]
..........
***Warning*** The account: tom has empty password! Please contact your administrator!
........
[root@butter ~]# cat /etc/shadow|grep tom
tom::15708:0:99999:7:::

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Don't rush to claim that you have found a bug

When you are having problems with a piece of software, don't claim you have found a bug unless you are very, very sure of your ground. Hint: unless you can provide a source-code patch that fixes the problem, or a regression test against a previous version that demonstrates incorrect behavior, you are probably not sure enough. This applies to webpages and documentation, too; if you have found a documentation “bug”, you should supply replacement text and which pages it should go on.

Remember, there are many other users that are not experiencing your problem. Otherwise you would have learned about it while reading the documentation and searching the Web (you did do that before complaining, didn't you?). This means that very probably it is you who are doing something wrong, not the software.

The people who wrote the software work very hard to make it work as well as possible. If you claim you have found a bug, you'll be impugning their competence, which may offend some of them even if you are correct. It's especially undiplomatic to yell “bug” in the Subject line.

When asking your question, it is best to write as though you assume you are doing something wrong, even if you are privately pretty sure you have found an actual bug. If there really is a bug, you will hear about it in the answer. Play it so the maintainers will want to apologize to you if the bug is real, rather than so that you will owe them an apology if you have messed up.