python3 mime and file object not working - python-3.6

Question

I'm trying to use the below mail function for python3 which is throwing error NameError: name 'file' is not defined which its works perfectly for python2.
I got to know file() is not supported in Python 3 what will be substitute of file.
#!/usr/bin/env python3
from subprocess import Popen, PIPE
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
import os
############ File comparison & sendmail part starts here ########
def ps_Mail():
filename = "/tmp/ps_msg"
f = file(filename)
if os.path.exists(filename) and os.path.getsize(filename) > 0:
mailp = Popen(["/usr/sbin/sendmail", "-t", "-oi"], stdin=PIPE)
msg = MIMEMultipart('alternative')
msg['To'] = "sam#seemac.com"
msg['Subject'] = "Uhh!! Unsafe process seen"
msg['From'] = "psCheck#seemac.com"
msg1 = MIMEText(filename.read(), 'text')
msg.attach(msg1)
mailp.communicate(msg.as_string())
ps_Mail()

Answer 1

I have edited your code and this should work, please try this...
There are two key things to change universal_newlines=True and use open() instead of file().
#!/usr/bin/env python3
from subprocess import Popen, PIPE
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
import os
############ File comparison & sendmail part starts here ########
def ps_Mail():
filename = "/tmp/ps_msg"
f = open(filename)
if os.path.exists(filename) and os.path.getsize(filename) > 0:
mailp = Popen(["/usr/sbin/sendmail", "-t", "-oi"], stdin=PIPE, universal_newlines=True)
msg = MIMEMultipart('alternative')
msg['To'] = "sam#seemac.com"
msg['Subject'] = "Uhh!! Unsafe process seen"
msg['From'] = "psCheck#seemac.com"
msg1 = MIMEText(filename.read(), 'text')
msg.attach(msg1)
mailp.communicate(msg.as_string())
ps_Mail()
For more details....
What is the difference between using universal_newlines=True (with bufsize=1) and using default arguments with Popen
The default values are: universal_newlines=False (meaning input/output is accepted as bytes, not Unicode strings plus the universal newlines mode handling (hence the name of the parameter though text_mode might have been a better name here) is disabled -- you get binary data as is (unless POSIX layer on Windows messes it up) and bufsize=-1 (meaning the streams are fully buffered -- the default buffer size is used).
universal_newlines=True uses locale.getpreferredencoding(False) character encoding to decode bytes (that may be different from ascii encoding used in your code).
If universal_newlines=False then for line in Robocopy.stdout: iterates over b'\n'-separated lines. If the process uses non-ascii encoding e.g., UTF-16 for its output then even if os.linesep == '\n' on your system; you may get a wrong result. If you want to consume text lines, use the text mode: pass universal_newlines=True or use io.TextIOWrapper(process.stdout) explicitly.
The second version does include universal_newlines and therefore I specify a bufsize.
In general, It is not necessary to specify bufsize if you use universal_newlines (you may but it is not required). And you don't need to specify bufsize in your case. bufsize=1 enables line-bufferred mode (the input buffer is flushed automatically on newlines if you would write to process.stdin) otherwise it is equivalent to the default bufsize=-1.