pdb在python程序中应用
1.什么是pdb？
pdb是python提供的调试程序的一种工具。
2.为什么需要pdb模块？
当我们的程序越写越大的时候，我们用print xxx 这种方式打断点，调试，非常不方便，这个时候我们需要专业的调试工具
3 如何使用pdb模块？
#!/usr/bin/env python
#coding:utf-8
import pdb
def a():
print "this is a"
def b():
print "this is b"
def c():
print "this is c"
def main():
pdb.set_trace()
a()
print "a is done"
print "---------------"
pdb.set_trace()
b()
print "b is done"
print "---------------"
pdb.set_trace()
c()
print "c is done"
print "--------------"
main()
我们写了这样一个程序，在行首import了pdb模块
然后在需要打断点插入这么一行代码 pdb.set_trace()，然后我们在执行的时候就变成这样
root@SSS:/data/last/rebootMon/nbNet# python pdb_test.py > /data/last/rebootMon/nbNet/pdb_test.py(18)main() -> a() (Pdb)
这个时候我们可以敲入对应指令，达到对应效果
n ---> 下一行：
start > /data/last/rebootMon/nbNet/pdb_test.py(19)main() -> a() (Pdb) n this is a > /data/last/rebootMon/nbNet/pdb_test.py(20)main() -> print "a is done" (Pdb) n a is done > /data/last/rebootMon/nbNet/pdb_test.py(21)main() -> print "---------------" (Pdb) n --------------- > /data/last/rebootMon/nbNet/pdb_test.py(22)main() -> pdb.set_trace() (Pdb) n > /data/last/rebootMon/nbNet/pdb_test.py(23)main() -> b() (Pdb) n this is b > /data/last/rebootMon/nbNet/pdb_test.py(24)main() -> print "b is done" (Pdb) n b is done > /data/last/rebootMon/nbNet/pdb_test.py(25)main() -> print "---------------" (Pdb) n --------------- > /data/last/rebootMon/nbNet/pdb_test.py(26)main() -> pdb.set_trace() (Pdb) n > /data/last/rebootMon/nbNet/pdb_test.py(27)main() -> c() (Pdb) n this is c > /data/last/rebootMon/nbNet/pdb_test.py(28)main() -> print "c is done" (Pdb) n c is done > /data/last/rebootMon/nbNet/pdb_test.py(29)main() -> print "--------------" (Pdb) n -------------- --Return--
我们可以看到当代码执行到一个断点的位置就会阻塞住，然后我们每敲一次n都会往下执行一行代码。
p ---> 打印：
假如我们程序是这样
#!/usr/bin/env python
#coding:utf-8
import pdb
def a(msg):
print "this is %s",msg
def b(msg):
print "this is %s"% msg
def c(msg):
print "this is %s"%msg
def main():
msg1 = 'a'
msg2 = 'b'
msg3 = 'c'
print "start"
pdb.set_trace()
a(msg1)
print "a is done"
print "---------------"
pdb.set_trace()
b(msg2)
print "b is done"
print "---------------"
pdb.set_trace()
c(msg3)
print "c is done"
print "--------------"
main()
我们想打印变量的值，就可以这样
root@SSS:/data/last/rebootMon/nbNet# python pdb_test.py start > /data/last/rebootMon/nbNet/pdb_test.py(22)main() -> a(msg1) (Pdb) p msg1 'a' (Pdb)
l ---> 展示：
root@SSS:/data/last/rebootMon/nbNet# python pdb_test.py start > /data/last/rebootMon/nbNet/pdb_test.py(22)main() -> a(msg1) (Pdb) l 17 msg1 = 'a' 18 msg2 = 'b' 19 msg3 = 'c' 20 print "start" 21 pdb.set_trace() 22 -> a(msg1) 23 print "a is done" 24 print "---------------" 25 pdb.set_trace() 26 b(msg2) 27 print "b is done" (Pdb) n this is %s a > /data/last/rebootMon/nbNet/pdb_test.py(23)main() -> print "a is done" (Pdb) n a is done > /data/last/rebootMon/nbNet/pdb_test.py(24)main() -> print "---------------" (Pdb) l 19 msg3 = 'c' 20 print "start" 21 pdb.set_trace() 22 a(msg1) 23 print "a is done" 24 -> print "---------------" 25 pdb.set_trace() 26 b(msg2) 27 print "b is done" 28 print "---------------" 29 pdb.set_trace()
b ---> 动态生成断点
我们先重写代码
#!/usr/bin/env python
#coding:utf-8
import pdb
def a(msg):
print "this is %s",msg
def b(msg):
print "this is %s"% msg
def c(msg):
print "this is %s"%msg
def main():
msg1 = 'a'
msg2 = 'b'
msg3 = 'c'
print "start"
while 1:
pdb.set_trace()
print "a is start"
a(msg1)
print "a is done"
print "---------------"
pdb.set_trace()
print "b is start"
b(msg2)
print "b is done"
print "---------------"
pdb.set_trace()
print "c is start"
c(msg3)
print "c is done"
print "--------------"
main()
-> print "a is start" (Pdb) l 18 msg2 = 'b' 19 msg3 = 'c' 20 print "start" 21 while 1: 22 pdb.set_trace() 23 -> print "a is start" 24 a(msg1) 25 print "a is done" 26 print "---------------" 27 pdb.set_trace() 28 print "b is start" (Pdb) b 25 Breakpoint 1 at /data/last/rebootMon/nbNet/pdb_test.py:25 (Pdb) n a is start > /data/last/rebootMon/nbNet/pdb_test.py(24)main() -> a(msg1) (Pdb) n this is %s a > /data/last/rebootMon/nbNet/pdb_test.py(25)main() -> print "a is done" (Pdb) n a is done > /data/last/rebootMon/nbNet/pdb_test.py(26)main() -> print "---------------"
我们 输入 b25 增加了一个断点
然后我们输入n 就跳到 25行。
q --退出：
退出交互
---使用动态变量
(Pdb) !x = 123 (Pdb) p x 123
