I am trying to run a shell script from a python script using the following:
from subprocess import call
call(['bash run.sh'])
This gives me an error, but I can successfully run other commands like:
call(['ls'])
You should separate arguments:
call(['bash', 'run.sh'])
call(['ls','-l'])
from subprocess import call
import shlex
call(shlex.split('bash run.sh'))
You want to properly tokenize your command arguments. shlex.split() will do that for you.
Source: https://docs.python.org/2/library/subprocess.html#popen-constructor
Note shlex.split() can be useful when determining the correct
tokenization for args, especially in complex cases:
When you call call() with a list, it expects every element of that list to correspond to a command line argument.
In this case it is looking for bash run.sh as the executable with spaces and everything as a single string.
Try one of these:
call("bash run.sh".split())
call(["bash", "run.sh"])
Related
I am using Ubuntu and I am running a command using the subprocess module. I am trying to find the maximum number of days a password can be use.
import subprocess
pass_max = subprocess.check_output('grep PASS_MAX_DAYS /etc/login.defs')
print(pass_max)
After running this code, I receive the error no such file or directory. How am I able to find the maximum number of days a password can be use?
check_output expects the command as a list:
subprocess.check_output(['grep', 'PASS_MAX_DAYS', '/etc/login.defs'])
Alternative is to pass shell=True, taking into account the security considerations
subprocess.check_output('grep PASS_MAX_DAYS /etc/login.defs', shell=True)
grep PASS_MAX_DAYS /etc/login.defs is being interpreted as a single executable, which can't be found. Use an array to pass an executable with arguments.
subprocess.check_output(['grep', 'PASS_MAX_DAYS', '/etc/login.defs'])
the argument of the function check_output has to be a list, so just add split at the end of your command string
import subprocess
pass_max = subprocess.check_output('grep PASS_MAX_DAYS /etc/login.defs'.split())
print(pass_max)
That should work
try this -
shell_output
By using the above you should be able to overcome all the challenges that otherwise appear with a subprocess module
Usage -
print(shell_output("your shell command here"))
I am trying to call a program with:
os.popen("program -s:'*' -c:'A;B;C;'")
However, it seems that it was interpreted as shell command:
program -s '*' -c 'A;B;C;'
which result incorrect behavior.
Can somebody help me on how to hanle such situdations where ':' is inside shell commandline?
Don't use os.popen(), use the subprocess module instead:
import subprocess
result = subprocess.check_output(['program', "-s:'*'", "-c:'A;B;C;'"])
This returns the output of the program without running it through a shell, passing in the arguments directly without any additional parsing.
I would like to be able to log the command used to run the current python script within the script itself. For instance this is something I tried:
#test.py
import sys,subprocess
with open('~/.bash_history','r') as f:
for line in f.readlines():
continue
with open('logfile','r') as f:
f.write('the command you ran: %s'%line.strip('\n'))
However the .bash_history does not seem to be ordered in chronological order. What's the best recommended way to achieve the above for easy logging? Thanks.
Update: unfortunately sys.argv doesn't quite solve my problem because I need to use process subtitution as input variables sometimes.
e.g. python test.py <( cat file | head -3)
What you want to do is not universally possible. As devnull says, the history file in bash is not written for every command typed. In some cases it's not written at all (user sets HISTFILESIZE=0, or uses a different shell).
The command as typed is parsed and processed long before your python script is invoked. Your question is therefore not related to python at all. Wether what you want to do is possible or not is entirely up to the invoking shell. bash does not provide what you want.
If your can control the caller's shell, you could try using zsh instead. There, if you setopt INC_APPEND_HISTORY, zsh will append to its history file for each command typed, so you can do the parse history file hack.
One option is to use sys.argv. It will contain a list of arguments you passed to the script.
import sys
print 'Number of arguments:', len(sys.argv), 'arguments.'
print 'Argument List:', str(sys.argv)
Example output:
>python test.py
Number of arguments: 1 arguments.
Argument List: ['test.py']
>python test.py -l ten
Number of arguments: 3 arguments.
Argument List: ['test.py', '-l', 'ten']
As you can see, the sys.argv variable contains the name of the script and then each individual parameter passed. It does miss the python portion of the command, though.
I was trying to use subprocess calls to perform a copy operation (code below):
import subprocess
pr1 = subprocess.call(['cp','-r','./testdir1/*','./testdir2/'], shell = True)
and I got an error saying:
cp: missing file operand
Try `cp --help' for more information.
When I try with shell=False , I get
cp: cannot stat `./testdir1/*': No such file or directory
How do I get around this problem?
I'm using RedHat Linux GNOME Deskop version 2.16.0 and bash shell and Python 2.6
P.S. I read the question posted in Problems with issuing cp command with Popen in Python, and it suggested using shell = True option, which is not working for me as I mentioned :(
When using shell=True, pass a string, not a list to subprocess.call:
subprocess.call('cp -r ./testdir1/* ./testdir2/', shell=True)
The docs say:
On Unix with shell=True, the shell defaults to /bin/sh. If args is a
string, the string specifies the command to execute through the shell.
This means that the string must be formatted exactly as it would be
when typed at the shell prompt. This includes, for example, quoting or
backslash escaping filenames with spaces in them. If args is a
sequence, the first item specifies the command string, and any
additional items will be treated as additional arguments to the shell
itself.
So (on Unix), when a list is passed to subprocess.Popen (or subprocess.call), the first element of the list is interpreted as the command, all the other elements in the list are interpreted as arguments for the shell. Since in your case you do not need to pass arguments to the shell, you can just pass a string as the first argument.
This is an old thread now, but I was just having the same problem.
The problem you were having with this call:
subprocess.call(['cp','-r','./testdir1/*','./testdir2/'], shell = False)
was that each of the parameters after the first one are quoted. So to the shell sees the command like this:
cp '-r' './testdir1/*' './testdir2/'
The problem with that is the wildcard character (*). The filesystem looks for a file with the literal name '*' in the testdir1 directory, which of course, is not there.
The solution is to make the call like the selected answer using the shell = True option and none of the parameters quoted.
I know that the option of shell=True may be tempting but it's always inadvisable due to security issues. Instead, you can use a combination of the subprocess and glob modules.
For Python 3.5 or higher:
import subprocess
import glob
subprocess.run(['cp', '-r'] + glob.glob('./testdir1/*') + ['./testdir2/'])
For Python 3.4 or lower:
import subprocess
import glob
subprocess.call(['cp', '-r'] + glob.glob('./testdir1/*') + ['./testdir2/'])
I am using Python to simplify some commands in Maven. I have this script which calls mvn test in debug mode.
from subprocess import call
commands = []
commands.append("mvn")
commands.append("test")
commands.append("-Dmaven.surefire.debug=\"-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000 -Xnoagent -Djava.compiler=NONE\"")
call(commands)
The problem is with line -Dmaven.surefire.debug which accepts parameter which has to be in quotas and I don't know how to do that correctly. It looks fine when I print this list but when I run the script I get Error translating CommandLine and the debugging line is never executed.
The quotas are only required for the shell executing the command.
If you do the said call directly from the shell, you probably do
mvn test -Dmaven.surefire.debug="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000 -Xnoagent -Djava.compiler=NONE"
With these " signs you (simply spoken) tell the shell to ignore the spaces within.
The program is called with the arguments
mvn
test
-Dmaven.surefire.debug=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000 -Xnoagent -Djava.compiler=NONE
so
from subprocess import call
commands = []
commands.append("mvn")
commands.append("test")
commands.append("-Dmaven.surefire.debug=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000 -Xnoagent -Djava.compiler=NONE")
call(commands)
should be the way to go.