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Python2.x利用commands模块执行Linux shell命令

用Python写运维脚本时,经常需要执行linux shell的命令,Python中的commands模块专门用于调用Linux shell命令,并返回状态和结果,下面是commands模块的3个主要函数:

1. commands.getoutput('shell command')

执行shell命令,返回结果(string类型)

复制代码 代码如下:
> commands.getoutput('pwd')
'/home/oracle'

2. commands.getstatus('file')

该函数已被python丢弃,不建议使用,它返回 ls -ld file 的结果(String)(返回结果太奇怪了,难怪被丢弃)

复制代码 代码如下:
> commands.getstatus('admin.tar')
'-rw-rw-r-- 1 oracle oracle 829440 Jan 29 10:36 admin.tar'

3. commands.getstatusoutput('shell command')

执行shell命令, 返回两个元素的元组tuple(status, result),status为int类型,result为string类型。

cmd的执行方式是{ cmd ; } 2>&1, 故返回结果包含标准输出和标准错误.

复制代码 代码如下:
> commands.getstatusoutput('pwd')
(0, '/home/oracle')

下面的一个脚本利用commands模块检测磁盘使用率,标识出大于10%的磁盘(百分比可根据实际情况调整,一般设为90%,本例为了更好的说明情况,设为10%):

import commands
threshold = 10
flag = False
title=commands.getoutput("df -h|head -1")
'''
Check sda disk space usage like below format:
/dev/sda2 20G 2.3G 17G 13% /
/dev/sda6 20G 306M 19G 2% /var
/dev/sda3 49G 2.8G 44G 7% /home
/dev/sda5 49G 4.5G 42G 10% /opt
/dev/sda1 194M 12M 172M 7% /boot
'''
chkDiskList=commands.getoutput("df -h|grep sda").split('\n')
usedPercents=commands.getoutput("df -h|grep sda|awk '{print $5}'|grep -Eo '[0-9]+'").split('\n')
for i in range(0,len(usedPercents)):
if int(usedPercents[i]) >= threshold:
chkDiskList[i] += ' ----Caution!!! space usage >= ' + str(threshold)
flag = True
'''
Check disk space usage like below format:
/dev/mapper/backup-backup_lv
751G 14G 699G 2% /backup
/dev/mapper/data-data_lv
751G 172G 540G 25% /data
''' 
chkDiskList_2=commands.getoutput("df -h|grep -v sda|grep -v tmp|grep -v system").split('\n')
usedPercents_2=commands.getoutput("df -h|grep -v map|grep -v sda|grep -v tmp|grep -v system|awk '{print $4}'|grep -Eo '[0-9]+'").split('\n')
for i in range(0,len(usedPercents_2)): 
if int(usedPercents_2[i]) >= threshold:
chkDiskList_2[i*2 + 1] += ' ----Caution!!! space usage >= ' + str(threshold)
flag = True
if flag == True:
#combine tile, chkDiskList, chkDisklist_2
result = [title,]
result.extend(chkDiskList)
result.extend(chkDiskList_2)
for line in result:
print line

假设当前的磁盘使用率如下:

[oracle@lx200 ~/admin/python]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 20G 2.3G 17G 13% /
/dev/sda6 20G 306M 19G 2% /var
/dev/sda3 49G 2.8G 44G 7% /home
/dev/sda5 49G 4.5G 42G 10% /opt
/dev/sda1 194M 12M 172M 7% /boot
tmpfs 18G 0 18G 0% /dev/shm
/dev/mapper/backup-backup_lv
751G 14G 699G 2% /backup
/dev/mapper/data-data_lv
751G 174G 539G 25% /data 

执行该脚本后的结果如下:

Filesystem Size Used Avail Use% Mounted on
/dev/sda2 20G 2.3G 17G 13% / ----Caution!!! space usage >= 10
/dev/sda6 20G 306M 19G 2% /var
/dev/sda3 49G 2.8G 44G 7% /home
/dev/sda5 49G 4.5G 42G 10% /opt ----Caution!!! space usage >= 10
/dev/sda1 194M 12M 172M 7% /boot
/dev/mapper/backup-backup_lv
751G 14G 699G 2% /backup
/dev/mapper/data-data_lv
751G 174G 539G 25% /data ----Caution!!! space usage >= 10

python Commands模块 使用方法

要获得shell命令的输出只需要`cmd`就可以了,
需要得到命令执行的状态则需要判断$"htmlcode">

> import commands
> commands.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
> commands.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
> commands.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
> commands.getoutput('ls /bin/ls')
'/bin/ls'
> commands.getstatus('/bin/ls')
'-rwxr-xr-x 1 root 13352 Oct 14 1994 /bin/ls'