Description of problem:
# ipa help cert
ipa: ERROR: non-public: OSError: [Errno 2] No such file or directory
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/ipalib/backend.py", line 141, in execute
    return self.Command[_name](*args, **options)
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 450, in __call__
    return self.__do_call(*args, **options)
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 478, in __do_call
    ret = self.run(*args, **options)
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 833, in run
    self.print_commands(name, outfile)
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 907, in print_commands
    writer.write()
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 716, in write
    open_in_pager(data)
  File "/usr/lib/python2.7/site-packages/ipalib/util.py", line 1206, in open_in_pager
    pager_process = subprocess.Popen([pager], stdin=subprocess.PIPE)
  File "/usr/lib64/python2.7/subprocess.py", line 711, in __init__
    errread, errwrite)
  File "/usr/lib64/python2.7/subprocess.py", line 1327, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
ipa: ERROR: an internal error has occurred

******Alexander Bokovoy*******
https://pagure.io/freeipa/issue/7746, this is fixed in RHEL 8.
******************************

****Customer's response on upgrade*****
unfortunately RHEL8 beta isn't really an option for us in the productive environment.
***************************************

********Investigation************
ipa was trying to print_commands().
goes for writing writer.write(), which is all good. But now, it finds buffer_length > terminal_height(), which should not happen and calls pager.

        def write(self):
            if self.buffer_length > get_terminal_height():
                data = "\n".join(self.buffer).encode("utf-8")
                open_in_pager(data)
            else:
                try:
                    for line in self.buffer:
                        print(line, file=self.outfile)
                except IOError:
                    pass

In open_in_pager(), ipa process cannot communicate with pager process. popen(). Perhaps its not running and throws. [Errno 2] No such file or directory

def open_in_pager(data):
    pager = os.environ.get("PAGER", "less")
    pager_process = subprocess.Popen([pager], stdin=subprocess.PIPE)

        def write(self):
            if self.buffer_length > get_terminal_height():
                data = "\n".join(self.buffer).encode("utf-8")
                open_in_pager(data)

PAGER is an environmental variable commonly used for specifying an application that accepts standard input and shows it on
standard output per page: more, less, etc. It is a traditional way to customize access to such pagers from multiple applications. See, for example, https://en.wikipedia.org/wiki/Terminal_pager.
*********************************

-Customer expects to backport fix in rhel7.

Version-Release number of selected component (if applicable):
ipa-server-4.6.4-10.el7.x86_64.rpm  

How reproducible:
sporadically in customer Env

Steps to Reproduce:
1.
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Actual results:


Expected results:


Additional info:
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