First of all, I am aware of the os.chdir() function and unfortunately it's not what I need.
I have a Python script that does stuff, including creating a folder new_folder. I am running this script from a terminal (it is added to the PATH)
C:\users\me\Desktop> my_script
and I want it to change the current working directory of my terminal, like this:
C:\users\me\Desktop> my_script
C:\users\me\Desktop\new_folder>
Is this even possible? And if so, how can I do it?
As stated in my comment, this is a very roundabout hacky way of doing it, and is probably a bad solution to your issue. that said, this is how it could be done:
if you use a batch file that calls a python script, that script would output the directory you wish to cd into:
example python script:
print("c:\your\directory")
example batch script:
for /f "delims=" %%i in ('C:\Path\To\python\python.exe your_python_script.py') do cd "%%i"
running this batch script yields:
c:\dir1>batchscript.bat
c:\dir1>for /f "delims=" %i in ('C:\Path\To\python\python.exe your_python_script.py') do cd "%i"
c:\dir1>cd "c:\dir2"
c:\dir2>
Notice we moved from dir1 to dir2 which is what I put in the output of my python script.
This will only work if your python script doesn't output anything other than the directory.
Again: not a good solution, but a solution.
Related
I want to implement a userland command that will take one of its arguments (path) and change the directory to that dir. After the program completion I would like the shell to be in that directory. So I want to implement cd command, but with external program.
Can it be done in a python script or I have to write bash wrapper?
Example:
tdi#bayes:/home/$>python cd.py tdi
tdi#bayes:/home/tdi$>
Others have pointed out that you can't change the working directory of a parent from a child.
But there is a way you can achieve your goal -- if you cd from a shell function, it can change the working dir. Add this to your ~/.bashrc:
go() {
cd "$(python /path/to/cd.py "$1")"
}
Your script should print the path to the directory that you want to change to. For example, this could be your cd.py:
#!/usr/bin/python
import sys, os.path
if sys.argv[1] == 'tdi': print(os.path.expanduser('~/long/tedious/path/to/tdi'))
elif sys.argv[1] == 'xyz': print(os.path.expanduser('~/long/tedious/path/to/xyz'))
Then you can do:
tdi#bayes:/home/$> go tdi
tdi#bayes:/home/tdi$> go tdi
That is not going to be possible.
Your script runs in a sub-shell spawned by the parent shell where the command was issued.
Any cding done in the sub-shell does not affect the parent shell.
cd is exclusively(?) implemented as a shell internal command, because any external program cannot change parent shell's CWD.
As codaddict writes, what happens in your sub-shell does not affect the parent shell. However, if your goal is to present the user with a shell in a different directory, you could always have Python use os.chdir to change the sub-shell's working directory and then launch a new shell from Python. This will not change the working directory of the original shell, but will leave the user with one in a different directory.
As explained by mrdiskodave
in Equivalent of shell 'cd' command to change the working directory?
there is a hack to achieve the desired behavior in pure Python.
I made some modifications to the answer from mrdiskodave to make it work in Python 3:
The pipes.quote() function has moved to shlex.quote().
To mitigate the issue of user input during execution, you can delete any previous user input with the backspace character "\x08".
So my adaption looks like the following:
import fcntl
import shlex
import termios
from pathlib import Path
def change_directory(path: Path):
quoted_path = shlex.quote(str(path))
# Remove up to 32 characters entered by the user.
backspace = "\x08" * 32
cmd = f"{backspace}cd {quoted_path}\n"
for c in cmd:
fcntl.ioctl(1, termios.TIOCSTI, c)
I shall try to show how to set a Bash terminal's working directory to whatever path a Python program wants in a fairly easy way.
Only Bash can set its working directory, so routines are needed for Python and Bash. The Python program has a routine defined as:
fob=open(somefile,"w")
fob.write(dd)
fob.close()
"Somefile" could for convenience be a RAM disk file. Bash "mount" would show tmpfs mounted somewhere like "/run/user/1000", so somefile might be "/run/user/1000/pythonwkdir". "dd" is the full directory path name desired.
The Bash file would look like:
#!/bin/bash
#pysync ---Command ". pysync" will set bash dir to what Python recorded
cd `cat /run/user/1000/pythonwkdr`
I have a question about running a bash script in a python file. First, let me explain the situation. I have multiple python files: for each city in Mali, I am able to create a weather forecast in python (therefore is have created multiple python files: e.g. gao.py, bamba.py, etc.) One of the steps in each python file, is to run a bash script that creates audiofiles in .wav format, and places them in a folder /converted. Now, my question the following:
How do I change the bash script in such a way, that when gao.py is running, a folder /converted/gao will be created, and when for example bamba.py is running, a folder converted/bamba is created?
This is the current bash script:
#!/bin/bash
if [ ! -d converted/gao ]
then
mkdir converted/gao;
fi;
However, when I run the script above, each city will places his files in converted/gao, which is not what I want. I hope somebody knows how to fix this issue.
Use __ file__ for accessing the filename of script in python. And then pass it as argument to bash script. After that access the argument in bash script using $1.
as following samples:
Python Script hello.py
import os
script_filename = __file__
# function to execute the shell script
os.system("./bashfile.sh {}".format(script_filename))
Sample Bash Script bashfile.sh
#!/bin/bash
script_name=$1
# now use the script_name as you like in your script.
echo $script_name
I have a folder called TEST with inside :
script.py
script.sh
The bash file is :
#!/bin/bash
# Run the python script
python script.py
If I run the bash file like this :
./TEST/script.sh
I have the following error :
python: can't open file 'script.py': [Errno 2] No such file or directory
How could I do, to tell my script.sh to look in the directory (which may change) and to allow me to run it for inside the TEST directory ?
Tricky, my python file run a sqlite database and I have the same problem when calling the script from outside the folder, it didn't look inside the folder to find the database!
Alternative
You are able to run the script directly by adding this line to the top of your python file:
#!/usr/bin/env python
and then making the file executable:
$ chmod +x script.py
With this, you can run the script directly with ./TEST/script.py
What you asked for specifically
This works to get the path of the script, and then pass that to python.
#!/bin/sh
SCRIPTPATH="$( cd "$(dirname "$0")" ; pwd -P )"
python "$SCRIPTPATH/script.py"
Also potentially useful:
You mentioned having this problem with accessing a sqlite DB in the same folder, if you are running this from a script to solve this problem, it will not work. I imagine this question may be of use to you for that problem: How do I get the path of a the Python script I am running in?
You could use $0 which is the name of the currently executing program, as invoked, combined with dirname which provides the directory component of a file path, to determine the path (absolute or relative) that the shell script was invoked under. Then, you can apply it to the python invocation.
This example worked for me:
$ t/t.sh
Hello, world!
$ cat t/t.sh
#!/bin/bash
python "$(dirname $0)/t.py"
Take it a step farther and change your current working directory which will also be inherited by python, thus helping it to find its database:
$ t/t.sh; cat t/t.sh ; cat t/t.py ; cat t/message.txt
hello, world!
#!/bin/bash
cd "$(dirname $0)"
python t.py
with(open('message.txt')) as msgf:
print(msgf.read())
hello, world!
From the shell script, you can always find your current directory: Getting the source directory of a Bash script from within. While the accepted answer to this question provide a very comprehensive and robust solution, your relatively simple case only really needs something like
#!/bin/bash
dir="$(dirname "${BASH_SOURCE[0]}")"
# Run the python script
python "$(dir)"/script.py
Another way to do it would be to change the directory from which you run the script:
#!/bin/bash
dir="$(dirname "${BASH_SOURCE[0]}")"
# Run the python script
(cd "$dir"; python script.py)
The parentheses ((...)) around cd and python create a subprocess, so that the directory does not change for the rest of your bash script. This may not be necessary if you don't do anything else in the bash portion, but is still useful to have if you ever decide to say source your script instead of running it as a subprocess.
If you do not change the directory in bash, you can do it in Python using a combination of sys.argv\[0\], os.path.dirname and os.chdir:
import sys
import os
...
os.chdir(os.path.dirname(sys.argv[0]))
I currently have a folder structure that will contain a few python scripts which need to be fired from a certain folder but I would like to write a global script that runs each python script via a seperate script in each folder.
-Obtainer
--Persona
---Arthur
----start.sh
--Initialise.sh
-Persona
--Arthur
---lib
----pybot
-----pybot.py
When I run initialise I am aiming to make initialise run "start.sh" Arthur is the bot and there will be more folders with different names and initialise with find and fire each start.sh.
In initialise.sh I have:
#!/bin/bash
. ./Persona/Arthur/start.sh
In start.sh I have:
#!/bin/bash
python ../../../Persona/Arthur/lib/pybot/pybot.py
I get this error:
python: can't open file '../../../Persona/Arthur/lib/pybot/pybot.py': [Errno 2] No such file or directory
However if I run the start.sh itself from its directory it runs fine. This is because I assume it's running it from the proper shell and consequently directory. Is there a way to make the main script run the start.sh in it's own shell like it is being run by itself? The reason why is because the pybot.py saves a bunch of files to where the start script is and because there will be more than one bot I need them to save in each seperate folder.
In the first place, do not source when you mean calling it,
#!/bin/bash
. ./Persona/Arthur/start.sh
Don't do this.
Your script has a number of issue. It won't work because of your current working directory is uncertain. You'd better have your script derive the path to relieve yourself from the hustle of abs paths or relative paths.
The general code could be
script_dir=`dirname "${BASH_SOURCE[0]}"`
then you can use this to derive the path of your target file,
#!/bin/bash
script_dir=`dirname "${BASH_SOURCE[0]}"`
"$script_dir/Persona/Arthur/start.sh"
Your python invocation becomes:
#!/bin/bash
script_dir=`dirname "${BASH_SOURCE[0]}"`
python "$script_dir/../../../Persona/Arthur/lib/pybot/pybot.py"
This should work out properly.
Regarding BASH_SOURCE, check out https://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html
If you want the directory of start.sh to be cwd, you should call cd:
#!/bin/bash
script_dir=`dirname "${BASH_SOURCE[0]}"`
cd "$script_dir"
python "$script_dir/../../../Persona/Arthur/lib/pybot/pybot.py"
I have a simple bash script that allows cron to execute a series of Python scripts in a virtualenv. The script keeps raising No such file or directory errors.
~/nightly.sh works fine:
#!/bin/bash
source virt_env/myproject/bin/activate
cd virt_env/myproject/main
python script1.py
python script2.py
I want to keep everything in ~/virt_env/myproject/main/ to simplify deployment. I thought I could call bash virt_env/myproject/main/nightly.sh on this:
#!/bin/bash
MAINDIR=`dirname $0`
cd $MAINDIR
source ../bin/activate
python script1.py
python script2.py
but I get the No such file or directory. If I manually cd to ~/virt_env/myproject/main/, then I can run the main commands no problem. Clearly I'm missing something about how dirname and cd work in this context.
How can I point bash at the right place?
Solution
As proposed in the accepted answer, it's best to avoid calling cd from within the script and use an explicit path variable instead. Here's the working version of virt_env/myproject/main/nightly.sh:
#!/bin/bash
MAINDIR=`dirname $0`
echo "The main directory is" $MAINDIR
# Activate virtual environment
source $MAINDIR/../bin/activate
# Run Python scripts
python $MAINDIR/python1.py
python $MAINDIR/python2.py
Because the Python scripts are now called from an arbitrary path, I needed to update the python scripts to be smarter about path awareness as well.
This code fails because os.path.basename omits path information:
# works when called with "python python1.py"
# fails when called with "python $MAINDIR/python1.py"
CONFIG_FILE = os.path.basename(__file__)[:-3] + ".config"
f = open(CONFIG_FILE,"r")
Updating it to use os.path.abspath fixes the problem:
# works regardless of how it is called
CONFIG_FILE = os.path.abspath(__file__)[:-3] + ".config"
f = open(CONFIG_FILE,"r")
Perhaps it would simply be better to eliminate the 'cd' command. Invoke everything from a full path specification. In your example add $MAINDIR/ to the executables.
Your bash script can then be in any directory where the executables are reachable. You are not exposed to the problems of what happens when cd fails.
Example:
cd yourdir
rm -f yourglob # oops things got removed from where you started if yourdir did not exist.
Two things:
Are you sure you know what the dirname command is doing? It's going to remove the top-level directory as well as the leading slash on whatever you call it on. I would make absolutely sure that the output of dirname is exactly what you think it is.
For example, /home/user/ will output /home.
You're using ~, which references the $HOME variable in your environment. You didn't mention where the cron is listed, but make sure it's not being run as a different user. Root's ~ and your ~ will be two completely different directories.
That's all I can think of. I hope that helps!
Add echo $MAINDIR after
MAINDIR=`dirname $0`
cd $MAINDIR
So you can see, if the contents of MAINDIR is correct.
Also you can run sh with -x or add set -x to the beginning of the script to see what happens.