I'm writing an ipython macro that processes the output of a program. The thing is, the program can sometimes write to stderr , so if I do something like this :
out = !my_program
the out variable will not contain the output. I think it will contain the exit code ( correct me if I'm wrong ).
How can I capture both stdout and stderr streams?
foo 2>&1 means redirect all of the output, including handle 2 (that is, STDERR), from the foo command to handle 1 (that is, STDOUT)
so here out = !foo 2>&1 maybe good enough. below is the demo:
egg.py:
#!/usr/bin/env python
# -*- coding: utf8 -*-
def main():
print 'hello'
print 3/0
if __name__ == "__main__":
main()
IPython 0.10
In [5]: out = !egg.py
Traceback (most recent call last):
File "D:\python\note\egg.py", line 7, in <module>
main()
File "D:\python\note\egg.py", line 5, in main
print 3/0
ZeroDivisionError: integer division or modulo by zero
In [6]: out
Out[6]: SList (.p, .n, .l, .s, .grep(), .fields(), sort() available):
0: hello
In [7]: out = !egg.py 2>&1
In [8]: out
Out[8]: SList (.p, .n, .l, .s, .grep(), .fields(), sort() available):
0: hello
1: Traceback (most recent call last):
2: File "D:\python\note\egg.py", line 7, in <module>
3: main()
4: File "D:\python\note\egg.py", line 5, in main
5: print 3/0
6: ZeroDivisionError: integer division or modulo by zero
Hope this helps
2>&1 to duplicate <i>stderr</i> to <i>stdout</i>, for example) long before MS added support for it in their systems. Under UNIX it's generalized (you can redirect, duplicate and close other file descriptors if you know their numbers).
