Can't execute external program through system()? - php

I tried to compile my latex file in php script, but it can't call xelatex.
In php script:
system("/usr/bin/whoami");
system("/usr/bin/xelatex foo.tex 2>&1");
output:
myuser
sh: 1: /usr/bin/xelatex: not found
But in my terminal:
$ /usr/bin/whoami
=> myuser
$ /usr/bin/xelatex foo.tex
This is XeTeX, Version 3.1415926-2.2-0.9995.2 (TeX Live 2009/Debian)
...(successful output)...
I run php as myuser, and pass system() absolute path. And I turn safe_mode off. Why can't I still execute external programs?

Finally I contacted my system administrator and found the problem. The machine is in a NFS, so the apache and login shell is on different machines. There is no xelatex on the machine where apache is running.

Check the permission of the directory from where you running you PHP code. check for myuser permissions
just for verification try it with root.
Hope this help

Are you sure it's not the file 'foo.tex' which it is unable to find? Try having the shell output to a file, e.g. system("/usr/bin/xelatex ./foo.tex > ./test.out"); and see what luck you get then.

Related

Issues With PHP exec & shell_exec - Shell Script Execution

I've been unable to run php scripts that I need to use to start and stop webcam services that run on the local machine with the scripts. I can find nothing in the logs to indicate why the script doesn't' work.
I confess to being severely handicapped regarding PHP, especially server-side scripting.
The environment is Debian Jesse running Nginx with all required SSH and PHP modules installed
I have added www-data to the sudoers file with:
www-data ALL=(ALL) NOPASSWD: /var/www/html/start_webcam.sh
Enabled the $PATH environment for www-data at:
/etc/php5/fpm/pool.d/www.conf
The shell script resides in the .../html directory and runs from the terminal with no issues.
This is the code for both the php and shell scripts:
start_webcam.php:
<?php
echo exec('sudo bash /var/www/html/aspirebox/start_webcam.sh 2>&1, $output');
print_r($output);
?>
The $output and print_r stuff is there because it was the last thing I tried based on a post I found out here somewhere.
start_webcam.sh
#!/bin/bash
service motion start
Thanks in advance to anyone out here that has a clue. After 2 days of wrestling with this, I am sure that I do not.
according to Passing Variables to shell_exec()? you should change your code like this:
<?php
$output = exec('/var/www/html/aspirebox/start_webcam.sh 2>&1 ');
print_r($output);
?>
and let your bash script execute as all (no need to sudo bash):
chmod a+x /var/www/html/aspirebox/start_webcam.sh
Thank you very much - that worked.
I worked through getting the path straight for the directory the shell script runs in, and the correct path to run "service".
All I have now is to figure out why I'm getting "Failed to start motion.service: Access denied"
I've given www-data permission to run the script without a password on sudoers, have to keep digging.
Thanks again!

Copy remote file with rsync in php

I'm trying to execute with PHP a command (rsync) to copy folders and files from a remote server to a local folder.
This is the code I wrote in php. Command WORKS in SSH (local Terminal and remote with putty.exe), copying correctly the folders and the files.
But it doesn't work in PHP. What can I do? Do you know a better(secure/optimal) way to do this?
exec("echo superuserpassword | sudo -S sshpass -p 'sshremoteserverpassword' rsync -rvogp --chmod=ugo=rwX --chown=ftpuser:ftpuser -e ssh remoteserveruser#remoteserver.com:/path/files/folder /opt/lampp/htdocs/dowloadedfiles/", $output, $exit_code);
EDIT:
I had read this guide to create a link between my server and my local machine.
Now I can login with ssh in my remote machine without password.
I changed my command:
rsync -crahvP --chmod=ugo=rwX --chown=ftpuser:ftpuser remote.com:/path/to/remote/files /path/to/local/files/
This command works too in terminal, but when I send it with exec php command, it fails again, but I got another different error: 127.
As MarcoS told in his answer, I checked the error_log.
The messages are this:
ssh: relocation error: ssh: symbol EVP_des_cbc, version OPENSSL_1.0.0 not defined in file libcrypto.so.1.0.0 with link time reference
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: remote command not found (code 127) at io.c(226) [Receiver=3.1.1]
Well, after lot of try/error, I finished to cut the problem in the root:
I readed this guide (like the last one, but better explained) and I changed the php file that execute the rsync command to the remote server (where files are located) and run the rsync.php file there, and it worked perfectly.
To execute in the machine with the files (the files to copy and the rsync.php)
1.- ssh-keygen generates keys
ssh-keygen
Enter an empty passphrase and repeat empty passphrase again.
2.- ssh-copy-id copies public key to remote host
ssh-copy-id -i ~/.ssh/id_rsa.pub remoteserveraddressip(xxx.xxx.xxx.xxx)
The rsync.php file:
exec("rsync -crahvP /path/in/local/files/foldertocopy remoteuser#remoteserveraddress:/path/in/remote/destinationfolder/", $output, $exit_code);
After all of that, navigate to the rsync.php file and all must work. At least worked for me...
I suppose you are experiencing identity problems... :-)
On a cli, you are running the command as the logged-in user.
On PHP, you are running the command as the user your web server runs as (for example, apache often runs as www-data, or apache user...).
One possible solution I see (if the above is the problem real cause), is to add your user to web-server group...
I'd also suggest you to check the web-server error logs, to be sure about the real cause of the problem... :-)

PHP command not executed system(), exec() or passthru()

I am trying to run a command line file conversion using open office.
openoffice pdf filename.doc 2>&1
when i execute in command line as root it works fine and the file is converted. However when i pass the above command in a PHP file as apache user, it does not execute.
I tried all three PHP command line execution:
$command_output=system($command_line,$rtnval);
$command_output=exec($command_line,$rtnval);
$command_output=passthru($command_line,$rtnval);
Also,
echo print_r($rtnval);
echo print_r($command_output);
$rtnval returns 1 and $command_output 1. I am confused unable to know what is the linux (centos) response to above command passed. It is very frustration because unable to know what the system response when i try to execute the command.
I also included /etc/suders permission for apache to run the open office command.
apache ALL: (ALL) NOPASSWD: /path/to/openoffice
still the command is not execute in PHP as apache user.
What am i missing for PHP as apache user not to execute this command?
It could be that openoffice is not in PATH. Try to execute it with the full path.
To run your command as if you were the apache user, just try this in a shell:
# switch to superuser
sudo su -
# then switch to the apache user
su - www-data
You will find yourself in a quite restricted shell, from which it is usually not possible to start openoffice. Indeed, it requires a lot of environment, that would be unsafe to completely set up for apache anyway.
AFAIK, better create a dedicated user that is allowed to run your command (eg a regular "www-runner" user), then "su" to it from PHP. Other security measures include chroot'ing the dedidacted user, or using apparmor to limit what and where it is allowed to run. In any case, never let www-data run something as root by adding www-data to the sudoers: this is way too dangerous!
You can also have a look at libapache2-mod-suphp (a suid apache module to run php scripts with the owner permissions).It is easier to use than the dedicated suEXEC apache beast (http://httpd.apache.org/docs/2.0/suexec.html). The latter really is not for a quick fix ;)
It is possible that your php in apache runs in safe mode or what's it called, in which system() function and alike are disabled.
This answer, actually, assumes that what you call "running as apache user" is in fact running in apache environment, whatever it is.

php exec crontab not working

I trying on my local CentOS 5.3 server, when I try to execute below line in my php code from apache webserver
exec("crontab -l", $output, $arg);
The $arg reply 127 (command not found code)
Then I changed below code
exec("/usr/bin/crontab -l", $output, $arg);
The $arg reply 126 (Permission problem code)
Here is my current permission of
/usr/bin/crontab -rwsr-sr-x 1 root root 311288 Mar 15 2007 /usr/bin/crontab.
And there is no /etc/cron.allow and /etc/cron.deny file.
I already turned off Safe_mode in php. Any suggestion to solve this problem?
////////////////////////////////////////////////////////////////////////////////
I note that my problem is related to selinux.
It is working, when I disable selinux
echo 0 > /selinux/enforce
But I don't want to disable selinux, is there any option in selinux to allow crontab from apache?
Add /usr/bin to your shell env path
Add crontab to the same group like of the webserver
Try in php exec("echo $PATH") to see the path variable. You can also look for unsetenv and temporarly disable it
You can look in the php error log for a detailed description of the error but as you said you are familiar with Linux I can't teach you about user right management. A note to the env variable and the path variable it's not always sure the env variable get exported when you run a program. This is maybe the case with your problem. It means either the os is broken or you have to attach the env variable manually to your program. A workaround can be to look where the shell is looking for programs and symlink the program. In your error log it seems that crontab is in the folder /usr/bin. Also this seems not to be a programming question. Ask at server.stackexchange why crontab isn't found. For example my env looks like this:
LC_PAPER=de_DE
LC_ADDRESS=de_DE
LC_MONETARY=de_DE
AF_PIDDIR=/tmp/af-piddir
UPNP_ROOT=upnpav://
SHELL=/bin/sh
TERM=xterm
DISABLE_GATEWAY=1
GTK2_RC_FILES=/etc/hildon/theme/gtk-2.0/gtkrc
TMPDIR=/var/tmp
MMC_SWAP_LOCATION=/media/mmc1
LC_NUMERIC=de_DE
MMC_MOUNTPOINT=/media/mmc1
OLDPWD=/root
HILDON_FM_OBEX_ROOT=obex://
LAUNCHWRAPPER_NICE_KILL=/etc/osso-af-init/nice-kill-launch-wrapper.sh
INTERNAL_MMC_MOUNTPOINT=/home/user/MyDocs
OSSO_VERSION=RX-51_2009SE_20.2010.36-2_PR_MR0
USER=root
LS_COLORS=no=00:fi=00:di=00;36:ln=00;35:pi=40;33:so=01;35:bd=40;32;00:cd=40;32;00:or=01;05;37;41:mi=01;05;37;41:ex=00;33:.cmd=00;32:.exe=00;32:.com=00;32:.btm=00;32:.bat=00;32:.sh=00;32:.csh=00;32:.tar=00;31:.tgz=00;31:.arj=00;31:.taz=00;31:.lzh=00;31:.zip=00;31:.z=00;31:.Z=00;31:.gz=00;31:.bz2=00;31:.bz=00;31:.tz=00;31:.rpm=00;31:.cpio=00;31:.jpg=00;35:.gif=00;35:.bmp=00;35:.xbm=00;35:.xpm=00;35:.png=00;35:.tif=00;35:
LC_TELEPHONE=de_DE
SESSION_BUS_PID_FILE=/tmp/dbus_session_bus.pid.user
OSSO_PRODUCT_HARDWARE=RX-51
STATESAVEDIR=/tmp/osso-appl-states
LAUNCHWRAPPER_NICE_TRYRESTART=/etc/osso-af-init/nice-launch-wrapper-tryrestart.sh
OSSO_PRODUCT_FULL_NAME=Nokia N900
OSSO_PRODUCT_RELEASE_FULL_NAME=Maemo 5
OSSO_PRODUCT_RELEASE_NAME=Maemo 5
MYDOCSDIR=/home/user/MyDocs
PATH=/usr/bin/gnu:/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin
LC_MESSAGES=de_DE
OSSO_PRODUCT_SHORT_NAME=Nokia N900
SESSION_BUS_ADDRESS_FILE=/tmp/session_bus_address.user
LC_IDENTIFICATION=de_DE
PWD=/home/user/MyDocs
EDITOR=/usr/bin/nano -w -c
LANG=de_DE
ERR=0
LC_MEASUREMENT=de_DE
PS1=[\033[1;36m][[\033[0;36m]\u\h[\033[0;37m]:\w[\033[1;36m]][\033[m]$ [\033[0;37;00m]
ILLEGAL_FAT_CHARS=/:*?<>|
OSSO_PRODUCT_KEYBOARD=German
AF_DEFINES_SOURCED=1
SHLVL=1
HOME=/root
SDL_AUDIODRIVER=pulse
OSSO_SWAP=/home/user/MyDocs
OSSO_PRODUCT_RELEASE_VERSION=20.2010.36-2
LS_OPTIONS=--color
LAUNCHWRAPPER_TRYRESTART=/etc/osso-af-init/launch-wrapper-tryrestart.sh
OSSO_PRODUCT_NAME=N900
AF_INIT_DIR=/etc/osso-af-init
MMC_DEVICE_FILE=/dev/mmcblk0p1
LOGNAME=root
DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-eCbOI2qrVP,guid=cd1dea104334a338a9007b9700000014
LAUNCHWRAPPER=/etc/osso-af-init/launch-wrapper.sh
OSSO_PRODUCT_WLAN_CHANNEL=fcc/us
MAX_FILENAME_LENGTH=255
DISPLAY=:0.0
LAUNCHWRAPPER_NICE=/etc/osso-af-init/nice-launch-wrapper.sh
LC_TIME=de_DE
INTERNAL_MMC_SWAP_LOCATION=/home/user/MyDocs
LC_NAME=de_DE
OSSO_PRODUCT_REGION=Germany
_=/usr/bin/gnu/env
Just type env in the prompt.

gpg encryption failed: file open error

I have been going nuts with this..
I have gnupg installed on my CentOS server and I try to encrypt uploaded files (uploaded via a PHP page). On the server via the command line, it works perfectly. But via the php script, it fails with this error:
gpg: /path-to-my-file/my-file: encryption failed: file open error
The user apache (which I think is used to run the exec command) has read/write in the directory of the file.
The file is uploaded fine (I can see it afterward as I removed the deletion of the unencrypted file from my code) and can be deleted correctly via the php site.
the command I run is the following
/path-to-gpg/gpg --homedir=/path-to-my-home-gnupg/.gnupg -e -r therecipient#email the-unencrypted-file
Any idea how I could tackle this?
thanks
A few things to check:
Run system("ls " . escapeshellarg($file)) and check the result — is it file not found? Permission denied? That will help you debug.
Run system("whoami") to make sure PHP is running as who you think it is.
Run echo "<pre>ls " . escapeshellarg($file) . "</pre>" then copy+paste the command and run it from the shell to make sure that the path to the file is what you expected it to be.
Also, I believe CentOS runs SELinux by default… If you've got it installed, check the logs (in /var/log/) to see if SELinux is preventing Apache from executing GPG.
Try running the command with actual apache user privileges in verbose mode:
su apache -c /path-to-gpg/gpg -vv ...

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