Merge pull request #7453 from takluyver/check-latex-commands

Check for latex commands to improve error messages when commands are missing

IPython/nbconvert/exporters/pdf.py

@@ -7,6 +7,7 b' import subprocess'
 import os
 import sys
 
+from IPython.utils.process import find_cmd
 from IPython.utils.traitlets import Integer, List, Bool, Instance
 from IPython.utils.tempdir import TemporaryWorkingDirectory
 from .latex import LatexExporter
@@ -57,13 +58,18 b' class PDFExporter(LatexExporter):'
             or failed (False).
         """
         command = [c.format(filename=filename) for c in command_list]
-        #In windows and python 2.x there is a bug in subprocess.Popen and
+
+        # On windows with python 2.x there is a bug in subprocess.Popen and
         # unicode commands are not supported
         if sys.platform == 'win32' and sys.version_info < (3,0):
             #We must use cp1252 encoding for calling subprocess.Popen
             #Note that sys.stdin.encoding and encoding.DEFAULT_ENCODING
             # could be different (cp437 in case of dos console)
             command = [c.encode('cp1252') for c in command]        
+
+        # This will throw a clearer error if the command is not found
+        find_cmd(command_list[0])
+        
         times = 'time' if count == 1 else 'times'
         self.log.info("Running %s %i %s: %s", command_list[0], count, times, command)
         with open(os.devnull, 'rb') as null: