shell脚本学习

system: rhel 5.5

db: oracle 10.2.0.5.0

本人对shell脚本一窍不通，顶多只认识echo，if语句，连语法是怎样都不清楚，没关系，我就直接拿AIX上现有的系统监控脚本模仿修改了一下，修改后的脚本如下：

$ cat /oradata/db_monitor/hr_monitor.sh 
#!/usr/bin/ksh
#check file system
echo "========`date '+%Y-%m-%d %H:%M:%S'`=========="

echo "========BEGIN-OF-THE-SCRIPT-OUTPUT=========="
i=0
df -h|grep -v "tmpfs"|grep -v "Use"|awk '{print $5,$6}'|while read Use Filesystem
do
if [ "`echo ${Use}|awk -F% '{print $1}'`" -gt "80" ] 
then
   echo "Filesystem ${Filesystem} have use ${Use}!"
   i=1
fi
done
if [ ${i} -eq "0" ] 
then
   echo "Filesystem usage ok!"
fi
echo "========================="
if [ "`ps -ef|grep pmon|grep -v grep|wc -l`" -eq "1" ] 
then
  echo "Oracle is Running!"
  echo "========================="
else
  echo "Oracle is Down!"
  echo "========================="
fi


#check hr_tset login
sqlplus -s hr_test/hr_test << ! > /tmp/hr_test_db_connect
set heading off
set term off
set feedback off
select 1000/40 from dual
/
Exit
!


if [ "`cat /tmp/hr_test_db_connect|grep -v "^$"|awk '{print $1}'`" = "25" ]
then
  echo "Instance ytohrdb connect is OK!"
  echo "========================="
else
  echo "Instance ytohrdb connect is FAIL!"
  echo "========================="
fi


#check db tablespace
sqlplus -s system/system << ! > /tmp/tablespace_used
set heading off
set feedback off
set pagesize 0
@/oradata/db_monitor/shell_scripts/check_tablespace.sql
exit
!


if [ "`cat /tmp/tablespace_used`" != "" ]
then
   cat /tmp/tablespace_used |grep -v "^$"| while read line
   do
      tablespace=`echo $line | awk '{print $1}'`
      usage=`echo $line | awk '{print $4}'`
      free_mb=`echo $line |awk '{print $5}'`
      echo "Tablespace ${tablespace} has used ${usage}%,there are ${free_m}M Free Space!"
   done
   echo "==============END-OF-THE-SCRIPT-OUTPUT================"
else
        echo "All the tablespace was been checked! It's OK! "
        echo "==============END-OF-THE-SCRIPT-OUTPUT================"
fi 

其中，/oradata/db_monitor/shell_script/check_tablespace.sql的脚本如下：

column TABLESPACE_NAME format a30 HEADING "TABLESPACE_NAME"
column MEGS_ALLOC format 9999,999,999,999 HEADING "MEGS_ALLOC"
column USED_OF_MAX format 9999,999,999,999 HEADING "USED_OF_MAX"
column FREE_OF_MAX format 9999,999,999,999 HEADING "FREE_OF_MAX"
column MAX format 9999,999,999,999 HEADING "MAX"
  
SELECT SIZE_INFO.TABLESPACE_NAME,
       SIZE_INFO.MEGS_ALLOC,
       SIZE_INFO.MEGS_USED,
       SIZE_INFO.USED_OF_MAX,
       SIZE_INFO.FREE_OF_MAX,
       SIZE_INFO.MAX
FROM (
SELECT A.TABLESPACE_NAME,
       ROUND(A.BYTES_ALLOC / 1024 / 1024) MEGS_ALLOC,
       ROUND((A.BYTES_ALLOC - NVL(B.BYTES_FREE, 0)) / 1024 / 1024) MEGS_USED,
       ROUND((A.BYTES_ALLOC - NVL(B.BYTES_FREE, 0))*100/A.MAXBYTES) USED_OF_MAX,
       ROUND((A.MAXBYTES - A.BYTES_ALLOC + NVL(B.BYTES_FREE, 0))/1048576) FREE_OF_MAX,
       ROUND(A.MAXBYTES / 1048576) MAX
FROM (SELECT F.TABLESPACE_NAME,
             SUM(F.BYTES) BYTES_ALLOC,
             SUM(DECODE(F.AUTOEXTENSIBLE, 'YES', F.MAXBYTES, 'NO', F.BYTES)) MAXBYTES
        FROM DBA_DATA_FILES F
       GROUP BY TABLESPACE_NAME) A,
               (SELECT F.TABLESPACE_NAME, SUM(F.BYTES) BYTES_FREE
                  FROM DBA_FREE_SPACE F
                 GROUP BY TABLESPACE_NAME) B
         WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME(+)
) SIZE_INFO     
WHERE SIZE_INFO.USED_OF_MAX > 80;

上面SHELL脚本的一些代码，可以在HP-UX下执行原始SCRIPT看看：

$ date "+%Y-%m-%d %H:%M:%S"
2012-10-18 08:55:19

$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/cciss/c0d0p10    4.9G  453M  4.2G  10% /
/dev/cciss/c0d0p9     4.9G  1.6G  3.1G  34% /home
/dev/cciss/c0d0p8     4.9G  392M  4.3G   9% /var
/dev/cciss/c0d0p7     9.7G  151M  9.1G   2% /tmp
/dev/cciss/c0d0p6     9.7G  4.4G  4.9G  48% /usr
/dev/cciss/c0d0p5      30G  3.5G   25G  13% /opt
/dev/cciss/c0d0p2     436G  259G  154G  63% /oradata
/dev/cciss/c0d0p1     996M   40M  905M   5% /boot
tmpfs                  16G     0   16G   0% /dev/shm

$ df -h|grep -v "tmpfs"|grep -v "Use"

/dev/cciss/c0d0p10    4.9G  453M  4.2G  10% /
/dev/cciss/c0d0p9     4.9G  1.6G  3.1G  34% /home
/dev/cciss/c0d0p8     4.9G  392M  4.3G   9% /var
/dev/cciss/c0d0p7     9.7G  151M  9.1G   2% /tmp
/dev/cciss/c0d0p6     9.7G  4.4G  4.9G  48% /usr
/dev/cciss/c0d0p5      30G  3.5G   25G  13% /opt
/dev/cciss/c0d0p2     436G  259G  154G  63% /oradata
/dev/cciss/c0d0p1     996M   40M  905M   5% /boot

$ df -h|grep -v "tmpfs"|grep -v "Use"|awk '{print $5,$6}' 
10% /
34% /home
9% /var
2% /tmp
48% /usr
13% /opt
63% /oradata
5% /boot

$ df -h|grep -v "tmpfs"|grep -v "Use"|awk '{print $5}'|awk -F% '{print $1}'
10
34
9
2
48
13
63
5

$ps -ef|grep pmon|grep -v grep|wc -l

1

由AIX中的脚本修改过程中，连猜带分段测试，看每一步的执行结果，最终改写成在HP-UX下的监控脚本，各位朋友也可以根据本人HP-UX下的脚本来测试改写，相信不一需要把SHELL全部学完，才会写SHELL；另外，在改写的过程中，有些管道命令还是不太清楚，[例如awk -F%,-F后面跟上域分隔符%]其实免不了BAIDU一下了。(当然，并不是鼓励大家不要去学习SHELL基础，我这是赶鸭子上架，没办法了，才这样干的！大家不要误会哦！)。

总结：

其中比较有意思的是df -h|grep -v "tmpfs"|grep -v "Use"|awk '{print $5,$6}'|while read Use Filesystem,

根据df -h|grep -v "tmpfs"|grep -v "Use"|awk '{print $5,$6}' 的结果集，输出第5、6个参数，while read到Use、Filesystem两个参数里

do与done是循环，一起结合使用；

其中在后面的cat /tmp/tablespace_used |grep -v "^$"| while read line也有使用，同理,这里是将一行的值读入参数line;

另外，注意if与then使用时，必须分行，像本人以前是做开发的，习惯性地把if [ "`cat /tmp/tablespace_used`" != "" ] 后面直接接then，结果报错；