I have a module i created in linux kernel.
I want the module to receive parameters, and i want one of them to have reading and writing permissions.
So i defined :
module_param(param, int, S_IWUSR|S_IRUGO);
But for some reason when i go to /sys/module/mymodule/paramter/param and try to write to it does not give me permission (even using sudo)
Do you use sudo with echo like
sudo echo 1 > /sys/module/mymodule/paramter/param
this?
Redirection to a file does not work with sudo. Use e.g. tee instead:
echo 1|sudo tee /sys/module/mymodule/paramter/param
That way you can write to a file as root.
Apart from that, your module_param() call looks good.
Related
I am using Ubuntu via WSL 2.0 on Windows 10 and would like to run Texlive from the Windows command line. To do so I prepended the Texlive folder to the path in /etc/environment (I also tried a number of other locations eg. $HOME/.bashrc):
C:\Users\scott\Documents>wsl echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/mnt/c/Windows/system32:...
C:\Users\scott\Documents>wsl
scott#SCOTT-PC:/mnt/c/Users/scott/Documents$ echo $PATH
/usr/local/texlive/2020/bin/x86_64-linux:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/mnt/c/Windows/system32:...
Why is there a difference between these two paths? Is it possible to change the first PATH variable?
To be honest, when I first looked at this question, I thought it would be an easy answer. Oh how wrong I was. There are a lot of nuances to how this works.
Let's start with the fairly "easy" part, though. The main difference between the first method and the second:
wsl by itself launches into a login (and interactive) shell
the shell launched with wsl echo $PATH is neither a login shell nor an interactive shell
So the first will source both login scripts (e.g. ~/.profile) and interactive startup scripts (e.g. ~/.bashrc). The second form does not get to source either of these.
You can see this a different way (and get to the solution) with the following commands:
wsl -e bash -c 'echo $PATH'
wsl -e bash -li -c 'echo $PATH'
The -li forces bash to run as a login and interactive shell, thus sourcing all of the applicable startup scripts. And, as #bovquier points out in the comments, a single quote is needed here to prevent PowerShell from interpolating the $ before it gets to Bash. That, or escape it.
You should be able to run TeX Live the same way, just replacing the "echo $PATH" with the startup command you need for TeX Live.
A second option would be to create a script that both adds the path and runs the command, and just launch that script through wsl /path/to/script.sh
That said, I honestly don't think that your current login/interactive PATH is coming from /etc/environment. In my testing, at least, /etc/environment has no use in WSL, and that's to be expected. /etc/environment is only sourced by PAM modules, and with no login check performed by WSL, there's no reason to invoke PAM in either the wsl nor the wsl echo $PATH commands.
I'd expect that you still have the PATH setting in ~/.bashrc or somewhere similar), and that's where the shell is picking it up from at the moment.
While this isn't necessarily critical to understanding the answer, you might also wonder, if /etc/environment isn't used for setting the default (non-login, non-interactive) path in WSL, what is? The answer seems to be that it is hard-coded into the init that starts up WSL. That init is also what appends the Windows path (assuming you don't have that feature disabled in /etc/wsl.conf).
I am trying to run a simple command say ls -l on OpenBSD shell (uname -r: 6.4) using php 5.6.
<?php
$output = shell_exec('ls -l');
echo "<pre>$output</pre>";
?>
There is no output of above code. Just pre tag upon inspecting elements
So what is causing this issue? I tried using the same command using
System
Shell_exec
exec
No luck. What would be the cause of this ? Probably System/shell_exec not supported in OpenBSD's version of Php or something else.
Thanks in advance!
You haven't given enough information for a definitive answer, but my
guess is that you run php through php-fpm, which is by default chrooted
to /var/www. Since shell_exec and system first call /bin/sh and you
most likely didn't copy it to var/www/bin/sh it can't find your shell.
After that you'd also need to copy the binaries (in this case ls) to
your chroot and possible library dependencies (not needed for files
under /bin).
Hope this helps for illustrative purposes, but please don't use it in
production.
I have set up a php file to run that just echos hello.
<?php
echo hello;
?>
My cron job looks like this:
/usr/local/bin/php -f “/home/username/public_html/mls/test.php”
when my script runs i get a confirmation email that says:
Could not open input file: /home/username/public_html/mls/test.php
I don't know what is causing this. I am using godaddy's virtual private server with cpanel x installed. I have used the ssh to set permissions 777 on folder and file and still can not get it to run.
Any advice would be helpful. Thanks.
For some reason PHP cannot open the file. Try replacing /usr/local/bin/php -f with "ls -la" to try to crib some more information. Remember to NOT quote the file name in the crontab: php -f filename.php, not php -f "filename.php", unless it contains spaces -- and then it's better to use single quotes.
Possibly, try "ls -la /home", "ls -la /home/username", "ls -la ~/public_html" and so on.
Also try appending
2>&1
to the command line, in case only stdout is mailed to you (I don't really think so, but being sure costs little).
One other possibility
The crontab as it is refers /home/username/public_html/mls/test.php - that is, a public HTML directory inside username's commonest value for a home directory.
It is possible that the cron job is either not running with the appropriate user and privileges, or that the user it "sees" is actually a virtual user - there is no "/home/username" at all - and the "home directory" is elsewhere, possibly even existing just as long as the cron job runs. In this case the solution might be to refer to
~/public_html/mls/test.php
or, as described above, to first run a command such as pwd or ls -la to determine exactly where the cron job's current working directory is.
If this, too, fails, then another workaround could be to invoke the PHP HTTP handler via curl or lynx:
/usr/bin/curl http://www.thishostname.com/mls/test.php
Possibly using either some environment variable or curl header or _GET option to authenticate to the script as the cron job, and avoid it being accessible from the outside.
I'm attempting to pipe an email to PHP with my Postfix mail server, using the technique mentioned here and have encountered the following error...
Mar 16 22:52:52 s15438530 postfix/pipe[9259]: AD1632E84C63: to=<php#[myserver].com>, relay=plesk_virtual, delay=0.61, delays=0.59/0/0/0.02, dsn=4.3.0, status=deferred (temporary failure. Command output: /bin/sh: /var/www/vhosts/[myserver].com/httpdocs/clients/emailpipe/email2php.php: Permission denied 4.2.1 Message can not be delivered at this time )
I'd really appreciate if anyone could shed some light on this issue for me. I've tried 777'ing the emailpipe directory, to no avail. Where am I going wrong?
Many thanks.
From the postfix docs...
For security reasons, deliveries to command and file destinations are performed with the rights of the alias database owner. A default userid, default_privs, is used for deliveries to commands/files in root-owned aliases.
So you have two options, either set the default_privs in main.cf to match the ownership of the email2php file.
Alternatively, there should be a way to create an alias database that is owned by the user instead of postfix/nobody. I haven't tried this before though so can't advise.
I have fixed this issue by disabling the SELINUX.
Make sure that you have
#!/usr/bin/php
<?php
(or whatever your path to php is - do "which php" on the server)
at the top of each of your php scripts and that each of the php script files is executable
chmod +x /var/.../email2php.php
Also, make sure that you can test the script from the command line:
cat some_rfc822_email.txt | /var/.../email2php.php
and get the result that you want
To fix this issue, you'll want to chown or chmod /var/www/vhosts/[myserver].com/httpdocs/clients/emailpipe/email2php.php to executable by your postfix user. Alternately, you'll want to redefine this user to execute the file successfully.
Simply changing the permissions of your directory (unless you used -R) won't be sufficient.
To illustrate why this works, consider the following toy example:
<me>#harley:~$ touch test
<me>#harley:~$ ls -al test
-rw-r--r-- 1 <me> <me> 0 2012-03-26 23:44 test
<me>#harley:~$ sh test
<me>#harley:~$
<me>#harley:~$ ./test
bash: ./test: Permission denied
<me>#harley:~$ chmod 755 test
<me>#harley:~$ ./test
<me>#harley:~$
In order to execute a file directly through the running shell, it needs to be set as executable. Other invocations (for example, sh email2php.php or php email2php.php) only require read access, because they're chaining execution off a different file entirely.
For what's likely to be causing the issue in the first place, see here.
I've been advised to remove the return command from my bashrc file in order to allow Ruby Version Manager to function properly. Do I simply delete the return command, or do I replace it with some other command? I am hesitant to mess with my System-wide shell without some proper direction. But I would really like to get RVM working as it is a time saver.
My bashrc is located in the etc directory and looks like this:
# System-wide .bashrc file for interactive bash(1) shells.
if [ -z "$PS1" ]; then
return
fi
PS1='\h:\W \u\$ '
# Make bash check its window size after a process completes
shopt -s checkwinsize
if [[ -s /Users/justinz/.rvm/scripts/rvm ]] ; then source /Users/justinz/.rvm/scripts/rvm ; fi
The last line, is an insert, described in the RVM installation.
I wouldn't. That return is probably there for a good reason. It obviously doesn't want to execute anything after that if the PS1 variable is empty.
I would just move the inserted line up above the if statement.
In addition, if that's actually in the system-wide bashrc file, you should be using something like:
${HOME}/.rvm/scripts/rvm
rather than:
/Users/justinz/.rvm/scripts/rvm
I'm sure Bob and Alice don't want to run your startup script.
If it's actually your bashrc file (in /Users/justinz), you can ignore that last snippet above.
The last line uses a file in a specific user's home directory, and as such should not be in the system-wide bashrc, since only root and that user will have access to that file. Best to place it in that user's ~/.bashrc instead.