We Keep Coding

How to use input() function of Python in bash script?

I am trying to integrate a Python script into a bash script. However when I use the input() function, I am getting an EOFError. How can I fix this problem?
#!/bin/bash
python3 <<END
print(input(">>> "))
END

You cannot source both the script and the user input through the program's standard input. (That's in effect what you're trying to do. << redirects the standard input.)
Ideally, you would provide the script as command line argument instead of stdin using -c SCRIPT instead of <<EOF heredoc EOF:
#!/bin/bash
python3 -c 'print(input(">>> "))'
Note that you may need to mind your quoting and escaping in case you have a more complicated Python script with nested quotes.
You can still let the script run over multiple lines, if you need to:
#!/bin/bash
python3 -c '
import os.path
path_name = input("enter a path name >>> ")
file_exists = os.path.exists(path_name)
print("file " + path_name + " " +
("exists" if file_exists else "does not exist"))
'
Note that you will get into trouble when you want to use single quotes in your Python script, as happens when you want to print doesn't instead of does not.
You can work around that using several approaches. The one I consider most flexible (apart from putting you into quoting hell) is surrounding the Python script with double quotes instead and properly escape all inner double quotes and other characters that the shell interprets:
#!/bin/bash
python3 -c "
print(\"It doesn't slice your bread.\")
print('But it can', 'unsliced'[2:7], 'your strings.')
print(\"It's only about \$0. Neat, right?\")
"
Note that I also escaped $, as the shell would otherwise interpret it inside the surrounding double quotes and the result may not be what you wanted.

Splitting a large file in python by calling a command line function

I am trying to split a file into a number of parts via a python script:
Here is my snippet:
def bashCommandFunc(commandToRun):
process = subprocess.Popen(commandToRun.split(), stdout=subprocess.PIPE)
output = process.communicate()
return output
filepath = "/Users/user/Desktop/TempDel/part-00000"
numParts = "5"
splitCommand = "split -l$((`wc -l < " + filepath + "/" + numParts + ")) " + filepath
splitCommand:
'split -l$((`wc -l < /Users/user/Desktop/TempDel/part-00000`/5)) /Users/user/Desktop/TempDel/part-00000'
If I run this command on a terminal, it splits the file as it's supposed to, but it fails for the above defined subprocess function.
I have tested the function for other generic commands and it works fine.
I believe the character " ` " (tilde) might be an issue,
What is the work around to getting this command to work?
Are there some better ways to split a file from python into "n" parts.
Thanks

You'll have to let Python run this line via a full shell, rather than trying to run it as a command. You can do that by adding shell=True option and not splitting your command. But you really shouldn't do that if any part of the command may be influenced by users (huge security risk).
You could do this in a safer way by first calling wc, getting the result and then calling split. Or even implement the whole thing in pure Python instead of calling out to other commands.
What happens now is that you're calling split with first parameter -l$((``wc, second parameter -l, etc.

subprocess module works but not exactly working

I am trying to replace the os.system with subprocess module (referencing from here), however though it seems to work (displaying the result in the script editor) but it is actually not working.
def convert_text(inImg, outImg, texImg):
if not os.path.exists(texImg):
Image.open(inImg).save(outImg)
#os.system('/apps/Linux64/prman-18.0/bin/txmake ' + outImg + ' ' + texImg)
subprocess.Popen("/apps/Linux64/prman-18.0/bin/txmake" + outImg + " " + texImg, shell = True)
os.remove(outImg)
print "Done converting " + inImg
The above code is supposed to look for any image files, converting it into .tif then followed by .tex. Though the results may state Done converting /user_data/texture/testTexture_01.tga, in actual fact there isn't any .tex files to be found in the directory. (there should be .tex files located at /user_data/texture, within where the image file is located)
I also tried to write it as subprocess.Popen('/apps/Linux64/prman-18.0/bin/txmake %s %s'% (outImg, texImg), shell = True) but it ain't working.
EDIT: I am running the following code in Maya as I am implementing that in that software
Am I doing it wrong in some ways?

subprocess.Popen takes a list of arguments. ie try:
subprocess.Popen(["/apps/Linux64/prman-18.0/bin/txmake", outImg, texImg])
update: removed shell=True

Popen is non-blocking, so it's not actually complete when the call returns. Because you're removing outImg right after the Popen call starts, the command is probably failing. Use subprocess.call instead, which will block until the command is finished:
subprocess.call(["/apps/Linux64/prman-18.0/bin/txmake", outImg, texImg])

As #suhail said, Popen takes a list of arguments, but (as of right now) his example code is wrong. It should look like this:
#os.system('/apps/Linux64/prman-18.0/bin/txmake ' + outImg + ' ' + texImg)
subprocess.Popen(["/apps/Linux64/prman-18.0/bin/txmake", outImg, texImg])
You should not use shell = True unless you've verified that outImg and texImg have no characters with special meaning to the shell (quote marks, spaces, asterisks, etc.) in them. With shell = True, those characters would be processed by the shell, and the results will probably not be what you expect. What you want is shell = False (which is the default), so that filenames with quote marks, spaces, etc. will be properly backslash-escaped before being passed to the shell.
UPDATE: You probably want to use subprocess.call(), not subprocess.Popen(). See the subprocess module documentation: call() will wait for the command to complete, then return the integer return code (which will be 0 if no errors occurred). You should capture that return code and test it, then only delete outImg if there were no errors. E.g.,:
def convert_text(inImg, outImg, texImg):
if not os.path.exists(texImg):
Image.open(inImg).save(outImg)
#os.system('/apps/Linux64/prman-18.0/bin/txmake ' + outImg + ' ' + texImg)
retcode = subprocess.call("/apps/Linux64/prman-18.0/bin/txmake", outImg, texImg)
if (retcode == 0):
os.remove(outImg)
else:
print "txmake returned error code " + str(retcode)
print "Done converting " + inImg
Read the documentation for more details on what you can do with call().

Permission error when running jar from python

I have a .jar archive that loads a file and then does some things with it and writes it to the disk again.
If I call this .jar directly from the command prompt, everything works. But when I try to do it from within python, I get the following error:
Input file ("C:\xxx.txt") was not found or was not readable.
This is my python code:
import sys, os, subprocess
if os.path.isdir(sys.argv[1]):
for file in os.listdir("."):
print (" ".join(['java', '-jar', sys.argv[2], 'd', "\"" + os.path.abspath(file) + "\"", "\""+os.path.join(os.path.join(os.path.abspath(os.path.dirname(file)), "output"), file) + "\""]))
subprocess.call(['java', '-jar', sys.argv[2], 'd', "\"" + os.path.abspath(file) + "\"", "\""+os.path.join(os.path.join(os.path.abspath(os.path.dirname(file)), "output"), file) + "\""])
When I copy the printed statement into the commandline, the jar executes perfectly; everything works. I tried running cmd as an admin, but that didn't help.

The problem is the extra quotes you're adding. When you pass subprocess a list of args, it already quotes them appropriately; if you quote them yourself, it'll end up quoting your quotes, so instead of passing an argument that, when unquoted, means C:\xxx.txt, you'll be passing an argument that, when unquoted, means "C:\xxx.txt", which is not a valid pathname.
The rule of thumb for Windows* is: If you know exactly what each argument should be, pass them as a list, and don't try to quote them yourself; if you know exactly what the final command-line string should be, pass it as a string, and don't try to break it into a list of separate arguments yourself.
* Note that this is only for Windows. On POSIX, unless you're using shell=True, you should basically never use a string.

Passing shell commands with Python os.system() or subprocess.check_call()

I'm trying to call 'sed' from Python and having troubles passing the command line via either subprocess.check_call() or os.system().
I'm on Windows 7, but using the 'sed' from Cygwin (it's in the path).
If I do this from the Cygwin shell, it works fine:
$ sed 's/&nbsp;/\ /g' <"C:foobar" >"C:foobar.temp"
In Python, I've got the full pathname I'm working with in "name". I tried:
command = r"sed 's/&nbsp;/\ /g' " + "<" '\"' + name + '\" >' '\"' + name + '.temp' + '\"'
subprocess.check_call(command, shell=True)
All the concatenation is there to make sure I have double quotes around the input and output filenames (in case there are blank spaces in the Windows file path).
I also tried it replacing the last line with:
os.system(command)
Either way, I get this error:
sed: -e expression #1, char 2: unterminated `s' command
'amp' is not recognized as an internal or external command,
operable program or batch file.
'nbsp' is not recognized as an internal or external command,
operable program or batch file.
Yet, as I said, it works OK from the console. What am I doing wrong?

The shell used by subprocess is probably not the shell you want. You can specify the shell with executable='path/to/executable'. Different shells have different quoting rules.
Even better might be to skip subprocess altogether, and write this as pure Python:
with open("c:foobar") as f_in:
with open("c:foobar.temp", "w") as f_out:
for line in f_in:
f_out.write(line.replace(' ', ' '))

I agree with Ned Batchelder's assessment, but think what you might want to consider using the following code because it likely does what you ultimately want to accomplish which can be done easily with the help of Python's fileinput module:
import fileinput
f = fileinput.input('C:foobar', inplace=1)
for line in f:
line = line.replace(' ', ' ')
print line,
f.close()
print 'done'
This will effectively update the given file in place as use of the keyword suggests. There's also an optional backup= keyword -- not used above -- which will save a copy of the original file if desired.
BTW, a word of caution about using something like C:foobar to specify the file name because on Windows it means a file of that name in whatever the current directory is on drive C:, which might not be what you want.

I think you'll find that, in Windows Python, it's not actually using the CygWin shell to run your command, it's instead using cmd.exe.
And, cmd doesn't play well with single quotes the way bash does.
You only have to do the following to confirm that:
c:\pax> echo hello >hello.txt
c:\pax> type "hello.txt"
hello
c:\pax> type 'hello.txt'
The system cannot find the file specified.
I think the best idea would be to use Python itself to process the file. The Python language is a cross-platform one which is meant to remove all those platform-specific inconsistencies, such as the one you've just found.