IOError: [Errno 32] Broken pipe: Python

The problem is due to SIGPIPE handling. You can solve this problem using the following code:

from signal import signal, SIGPIPE, SIG_DFL
signal(SIGPIPE,SIG_DFL) 

See here for background on this solution. Better answer here.

To bring Alex L.'s helpful answer, akhan's helpful answer, and Blckknght's helpful answer together with some additional information:

• Standard Unix signal SIGPIPE is sent to a process writing to a pipe when there's no process reading from the pipe (anymore).

  • This is not necessarily an error condition; some Unix utilities such as head by design stop reading prematurely from a pipe, once they've received enough data.

• By default - i.e., if the writing process does not explicitly trap SIGPIPE - the writing process is simply terminated, and its exit code is set to 141, which is calculated as 128 (to signal termination by signal in general) + 13 (SIGPIPE's specific signal number).

• By design, however, Python itself traps SIGPIPE and translates it into a Python IOError instance with errno value errno.EPIPE, so that a Python script can catch it, if it so chooses - see Alex L.'s answer for how to do that.

• If a Python script does not catch it, Python outputs error message IOError: [Errno 32] Broken pipe and terminates the script with exit code 1 - this is the symptom the OP saw.

• In many cases this is more disruptive than helpful, so reverting to the default behavior is desirable:

  • Using the signal module allows just that, as stated in akhan's answer; signal.signal() takes a signal to handle as the 1st argument and a handler as the 2nd; special handler value SIG_DFL represents the system's default behavior:

    from signal import signal, SIGPIPE, SIG_DFL
    signal(SIGPIPE, SIG_DFL) 
    

I haven't reproduced the issue, but perhaps this method would solve it: (writing line by line to stdout rather than using print)

import sys
with open('a.txt', 'r') as f1:
    for line in f1:
        sys.stdout.write(line)

---

You could catch the broken pipe? This writes the file to stdout line by line until the pipe is closed.

import sys, errno
try:
    with open('a.txt', 'r') as f1:
        for line in f1:
            sys.stdout.write(line)
except IOError as e:
    if e.errno == errno.EPIPE:
        # Handle error

You also need to make sure that othercommand is reading from the pipe before it gets too big - https://unix.stackexchange.com/questions/11946/how-big-is-the-pipe-buffer