I need to access /boot so i can change a file continuously involving a PHP script ( To enable a raspberry pi and disable by changing start_x=' ' ) . However this involves me changing the permissions of boot.
I have tried sudo chown -R /boot and still get permissions denied when running as root. Also tried FTP and changing the folder of boot to let users modify content however this did not work either.
Is there anyway going around this???
<?php
$myfile = fopen("config.txt", "w") or die("Unable to open file!");
[...]
?>
Update: I have tried to do chmod 775 /boot/config.txt and also symlink (ran successfully) so i have a shortcut in /var/www/ however when trying to save the php script into config.txt (in www) still get permission denied even though that shortcut is set to 775. The issue still persists with changing to change the permission of the original file under /boot .
Try launching a shell and trying your command:
sudo sh -c "echo 123 >/boot/test"
works but
sudo echo 123 >/boot/test
fails. I don't understand the cause of this difference.
The user running as php would need permissions set in sudoers.d to execute the commands you need.
Try like this:
sudo chown -R root /root/boot
PHP runs under a restricted account and can't write anything in the boot partition.
You might be able to add the account PHP runs as to the sudoers file, although it's a pretty huge security risk.
Related
I'm trying to execute a php script but i'm having this kind of errors:
Warning: file_put_contents(/sys/class/gpio/export): failed to open stream: Permission denied in /home/pi/php-gpio/src/PhpGpio/Gpio.php on line 99
Warning: file_put_contents(/sys/class/gpio/gpio17/direction): failed to open stream: Permission denied in /home/pi/php-gpio/src/PhpGpio/Gpio.php on line 103
I've tried to set up the permission in the $ sudo visudo like this:
www-data ALL=NOPASSWD: path/to/my/script
or
www-data ALL=NOPASSWD: ALL
but is not working, i'm able to execute this script only with sudo form the command line!
Thanks in advance!
If you using in your computer, you must change the default directory permission:
$ sudo chmod -R +w /sys/class/gpio/export
else if you run code in a server, in server panel and in section files (e.g. CPanel) change permission and add write right.
Another way is running exec() command:
<?php
exec('chmod -R +w /sys/class/gpio/export');
?>
However, php should have exec right and running with root!
I recently published a project that allows PHP to obtain and interact with a real Bash shell (as root if requested), it solves the limitations of exec() and shell_exec(). Get it here: https://github.com/merlinthemagic/MTS
After downloading you would simply use the following code:
$shell = \MTS\Factories::getDevices()->getLocalHost()->getShell('bash', true);
$return1 = $shell->exeCmd('/sys/class/gpio/export');
$return2 = $shell->exeCmd('/sys/class/gpio/gpio17/direction');
//the return will be a string containing the return of the command
echo $return1;
echo $return2;
In terms of security it is far better than running apache as root, or the wide open sudo permissions in your question. But letting PHP anywhere near root is always tricky.
The project i built achieves a root bash shell in one of 2 ways:
1) You allow apache the right to sudo python.
OR
2) You pass root credentials to the object every time you need a shell with root setup.
Pick your poison. :) Read the documentation.
I wrote a little PHP script that I'd like to call from Apache. I'm intending to use this to control pianobar.
If I execute the script directly from a root terminal, it works just fine, but if I try to run the script through the web server, nothing.
The fifo I created is at /home/dave/.config/pianobar/piano and the relevant lines in the PHP script look like this...
<?php
system("echo -n 'p' > /home/dave/.config/pianobar/piano"); //'p' pauses pianobar.
echo system('whoami');
?>
If I execute this script in a browser through Apache, it echoes 'www-data www-data' which tells me that safe mode is disabled and the system() command is working, but pianobar keeps playing. If I run this from a root terminal, it echoes back 'root' and pianobar pauses. If I execute this from a terminal under my own username, it echoes back 'dave' and pianobar still pauses.
The fifo I created /home/dave/.config/pianobar/piano was chmodded to 777. What gives? Is this a permissions issue somehow? Is PHP not allowing me to do anything useful with the system() command?
Check folder permissions:
stat --format '%a' /home/dave/.config/pianobar/piano
Set folder permissions for all files inside of folder:
sudo chmod -R 755 /home/dave/.config/pianobar/piano
Try, should work.
Okay so I want to change the file mode of a directory to 777 so I use the line
exec('chmod -R 777' . $dir);
where $dir is the directory path of the directory I wanna change
it doesn't seem to work but I don't get an error for it, also if the user I was executing the script from was a sudo user so I have to enter the password after I enter the command, how would I do this? Would it be something like exec('chmod -R 777' . $dir\n 'password'); ?
Information I get from this site
Execute system commands via PHP
Many a times we need to execute system commands on a Linux system – to delete a directory, or restart a service. However, since Apache does not run with root privileges, it is nearly impossible to use PHP’s exec(), system() or passthru() functions to achieve that.
The solution to this is very simple, specially on Ubuntu. The Apache’s user www-data need to be granted privileges to execute certain applications using sudo.
1.Run the command sudo visudo
2.At the end of the file, add the following
www-data ALL=NOPASSWD: /sbin/iptables, /usr/bin/du
This is assuming that you wish to run iptables and du using super user (root) privileges. However, if you wish to run every application using super user privileges, then add the following instead of what’s above
www-data ALL=NOPASSWD: ALL
3.That’s it, now use exec() in the following manner inside your .php script
exec ("sudo iptables -P FORWARD ACCEPT");
$handle = fopen('/Applications/XAMPP/xamppfiles/htdocs/test/file.txt', 'w');
I tried doing the above and every time I try it, the following statement appeared on my browser:
Warning:fopen(/Applications/XAMPP/xamppfiles/htdocs/test/file.txt)
[function.fopen]: failed to open stream: Permission denied in
/Applications/XAMPP/xamppfiles/htdocs/test/index.php on line 26.
I tried looking through answered questions with the same type of questions but most of the things I tried did not work. For example, writing the full directory...
Maybe, you have no premissions to acces the file. One of the answet, is that, you must change CHMOD to e.g. 777. You can co it with your ftp explorer or with PHP.
chmod("/somedir/somefile", 777);
By default when XAMPP is installed, the htdocs folder does not have any read permissions. You can change the permissions through the terminal like this.
cd /Application/XAMPP/xamppfiles/htdocs/test/
sudo chmod 0664 file.txt
Alternatively, you can recursively set all the permission level of all files and folders
cd /Application/XAMPP/xamppfiles/
sudo chmod -R 0664 htdocs/
You could chmod to 777, but that is risky security. What I'm guessing you really want is change ownership of the file. You can do this using chown. PHP usually runs as user www-data, so you'd run a command something like this.
sudo chown www-data:root path/to/file.ext
If you're file permission on the file was something normal like 664, that'd give PHP the 6 permission (Read and Write) instead of the 4 (just Read).
When I use chmod() to change permissions at run time, it gives me the below message:
Warning: chmod() [function.chmod]: Operation not permitted in /home/loud/public_html/readalbum.php
How can I remove this error and make the chmod function work?
$ sudo chmod ...
You need to either be the owner of the file or be the superuser, i.e., user root. If you own the directory but not the file, you can copy the file, rm the original, then mv it back, and then you will be able to chown it.
The easy way to temporarily be root is to run the command via sudo. ($ man 8 sudo)
In order to perform chmod, you need to be owner of the file you are trying to modify, or the root user.
This is a tricky question.
There a set of problems about file permissions. If you can do this at the command line
$ sudo chown myaccount /path/to/file
then you have a standard permissions problem. Make sure you own the file and have permission to modify the directory.
If you cannnot get permissions, then you have probably mounted a FAT-32 filesystem. If you ls -l the file, and you find it is owned by root and a member of the "plugdev" group, then you are certain its the issue. FAT-32 permissions are set at the time of mounting, using the line of /etc/fstab file. You can set the uid/gid of all the files like this:
UUID=C14C-CE25 /big vfat utf8,umask=007,uid=1000,gid=1000 0 1
Also, note that the FAT-32 won't take symbolic links.
Wrote the whole thing up at http://www.charlesmerriam.com/blog/2009/12/operation-not-permitted-and-the-fat-32-system/
You, or most likely your sysadmin, will need to login as root and run the chown command:
http://www.computerhope.com/unix/uchown.htm
Through this command you will become the owner of the file.
Or, you can be a member of a group that owns this file and then you can use chmod.
But, talk with your sysadmin.