I want to add a line in the crontab (on my local machine) which will run every five minutes. My problem is the command I am going to use requires sudo :
sudo indexer --config /usr/local/etc/sphinx.conf --all --rotate
Is there a way I can run the command without using sudo and without prompting for password ?
Thanks!
Put it in the crontab of root
sudo crontab -e
There you can put
indexer --config /usr/local/etc/sphinx.conf --all --rotate
All commands in this crontab will be executed as root. If you just du crontab -e as your current user, they will be executed under your users permissions.
Just append your command to the sudoer file list by using cmd visudo(this cmd requires root priviledge) as below:
<YOUR_USER_NAME> ALL = NOPASSWD:<ABSOLUTE-PATH-TO-CMD>
Take care of the ABSOLUTE-PATH-TO-CMD,It may become a security hole.
Its extremely dangerous to put applications in root's crontab unless the box is secured well from hackers. If by chance someone replaces the binaries (including libraries), you're gone!
A better way would be to chown all the files the binary accesses to an unprivileged user and run the job as the unprivileged user.
Any of the binary files the application uses should not be writeable by anyone except root.
run it as a root ? or sphinx user ? try to find out which user you need it to be run as and add it to that users cron
You can configure sudo not to ask password. Read man sudoers for how to do that. Search for NOPASSWD string.
Related
I created bash script on Linux Redhat with vim
My script is working well on an user.
I need to esxute on the same script this command
su - root with password
VGDISPLAY -v |grep "LV Status"
the probem is when I execute my script the part of the normal user is done
and the other part with root not done
my question how can I do to execute this
I need to switch in the same script to root
Best regards
I'd recommend not switching to the root user in the script for specific tasks/commands but assigning SUDO privileges to your user (by which you are running the script), and using sudo command in the script for the tasks/commands that need elevations.
Hint: By sudo command you may run a process on behalf of another user (root probably).
If you are not familiar with sudo command or how to assign SUDO privileges to a user, please see the following link or google it.
https://phoenixnap.com/kb/linux-sudo-command
PS. Providing SUDO privileges to a user is configurable whether to be used for all commands or limited commands. For testing purposes, you may configure the user to be able to run all commands with sudo to gain the privileges, but for production use it is strongly recommended to limit the user to be able to use only necessary commands with sudo and nothing more.
I have a script that runs iftop in text mode, cuts down the output to what I'm concerned in, and saves it to a text file along with the output of the date command (I am monitoring network usage on various interfaces over time). Only problem I'm having is I'm trying to run my script every 15 minutes via the crontab, and in order to run the iftop command I need sudo permissions. Does anyone know some way to change the permissions of iftop to make it so I don't need sudo permissions?
Alternatively if I can give the script the ability to run the command with sudo that would be fine by me as well. I tried adding the script to the sudoers file via sudo visudo and adding the line:
user ALL=(ALL) NOPASSWD: /home/user/network_usage.sh
but that didn't work...perhaps a result of executing from the crontab?
Thanks,
-Eric
A more granular approach would be to use:
# setcap cap_net_raw=eip $(which iftop)
This lets iftop capture packets but does not give the process full root privileges. In case of a security problem or bug with "iftop" its side effects would be much more limited.
Related: https://unix.stackexchange.com/questions/189750/how-can-i-run-script-without-root-to-sniff-network-libpcap
If you have root access on the machine the quick and dirty way:
chmod +s $(which iftop)
This will make it run w/ root privileges no matter who invokes it.
But I still think your sudo like should work.
You may use root's crontab to run the script.
If instead of crontab -e you use sudo crontab -e you will edit root's crontab. Tasks specified in that file will run under root's account and privileges.
Alternatively, you can set the setuid access flag for your script file. To do so first change the owner of the file to root, then enable setuid like this:
sudo chown root /home/user/network_usage.sh
sudo chmod +s-w /home/user/network_usage.sh
The setuid bit makes an executable file run with the effective UID of its owner.
Regardless of what approach you take, be very careful.
Make your script owned by root and don't let any other user write to it, otherwise it could ease a privilege escalation.
Be aware of the side effects of your setuid programs. If the script has setuid and may create or modify files, it might be used by someone else to modify or create files they aren't supposed to. Always check the manual before giving setuid to any program you haven't written.
Is there any suitable shell script for shutting down or restarting a Linux machine? I have tried a shell script for shutdown, but when I enter sudo shutdown it will ask for the password. How we can enter the password using the script?
Another, in my opinion cleaner approach:
Create a new file in /etc/sudoers.d/ with content:
%users ALL=NOPASSWD: /sbin/shutdown
%users ALL=NOPASSWD: /sbin/reboot
This causes sudo to not ask for the password, if any user of group "users" tries to execute a shutdown or reboot. Of course you can also specify another group, maybe a newly created group for finer control of reboot permissions.
More information about the other possible settings for sudo can be found in the Manpage.
Yes, use the -S switch which reads the password from STDIN:
$echo <password> | sudo -S <command>
So to shut down the machine, your command would be like this (just replace <password> with your password):
$echo <password> | sudo -S poweroff
Exposing your password is generally bad idea search for something that can protect / hide it. In the past I've used Jenkins plugins to do this while executing the scripts regularly.
if you really want to achieve it, you should write a script containing the shutdown command; make root be its owner, then set the SUID bit with the chmod command and give to it executable permission for everybody. When executed, the owner of the script would become root and no password should be asked.
For some reason I need, as user, to run without sudo a script script.sh which needs root privileges to work.
I saw as the only solution to put sudo INSIDE script.sh. Let's take an example :
script.sh :
#!/bin/sh
sudo apt-get update
Of course, if I execute this script, I get a prompt asking me for a password. Then I added to my sudoers file (at the end to override everything else) :
user ALL=(ALL:ALL) NOPASSWD:/path/to/script.sh
By the way, I also tried the line :
user ALL=(ALL) NOPASSWD:/path/to/script.sh
(I think I didn't fully understand the difference)
But this doesn't solve my problem if I don't use sudo to execute this script :
# ./script.sh
[sudo] password for user:
# sudo ./script.sh
Starts updating...
Well, so I say to myself "Ok, that means that if I have a file refered in sudoers as I did, it will work without prompt only if I call him with sudo, what is not what I want".
So, ok, I create another script script2.sh as following :
script2.sh
#!/bin/sh
sudo /path/to/script.sh
In fact it works. But I am not truly satisfied of this solution, particularly by the fact that I have to use 2 scripts for every command.
This post is then for helping people having this problem and searching for the same solution (I didn't find a good post on it), and perhaps have better solutions coming from you guys.
Feel free to share your ideas !
EDIT 1 :
I want to insist on the fact that this "apt-get update" was just an example FAR from whhat my script actually is. My script has a lot of commands (with some cd to root-access-only config files), and the solution can't be "Well, just do it directly with apt-get".
The principle of an example is to help the understanding, not to be excuse to simplify the answer of the general problem.
From my blog: IDMRockstar.com:
The kicker is that sometimes, I need to run commands as root. Here's the quick and dirty way I accomplish that without divulging the passwords:
#! /bin/bash
read -s -p "Enter Password for sudo: " sudoPW
echo $sudoPW | sudo -S yum update
This way the user is prompted for the password (and hidden from terminal) and then passed into commands as needed, so I'm not running the entire script as root =)
If you have a better, way, I'd love to hear it! I'm not a shell scripting expert by any means.
Cheers!
.: Adam
If you want to run sudo /usr/bin/apt-get update without a password, you need to have the sudoers entry:
user ALL=(ALL:ALL) NOPASSWD:/usr/bin/apt-get update
For the larger issue of the script as a whole, there are two possible approaches:
Approach 1
For each command in the script that needs sudo, create a line in sudoers specifically for that command. In this case, the script can be called normally:
./script1.sh
Approach 2
Place a line in sudoers for the script as a whole. When this is done, the individual commands do not need sudo. However, sudo must be used to start the script as in:
sudo ./script.sh
If your password isn't something you want to be very secure about, (maybe some testing server in the company etc.) you can elevate to sudo in the script via echo like:
echo YourPasswordHere | sudo -S Command
The prompt still prints the "enter password" text to output though. So don't expect it to be neat.
See this Askubuntu post
As you noted, the file that must appear in the sudoers configuration is the one that is launched by sudo, and not the one that runs sudo.
That being said, what we often do, is having something like
user ALL=(ALL:ALL) NOPASSWD:/path/to/script.sh
in the sudo configuration, where script.sh has all the commands that the script has to do.
Then we define either a Bash function or an alias so that script.sh is actually
sudo /path/to/script.sh
The only issue is if some commands must not be run as root, you need to insert some su - user -c "command" commands in the script.
In new /etc/sudoers.d/apt-get file, put single line:
user ALL=(ALL:ALL) NOPASSWD:/usr/bin/apt-get update
Fully qualified path to executable is required here.
Then use following in your script:
sudo apt-get update
Here, fully specified name is not required. Sudo uses PATH environment variable for executable resolution.
While changing and checking sudoers configuration, be sure to keep another root session open for error recovery.
I suggest you look at the sudo environment variables - specifically you can use (and check for) $SUDO_USER. Call your script with sudo (1 entry in sudoers), then do user stuff as SUDO_USER and root stuff as root.
As mentioned by Basilevs you need to add your user to the sudoers file in order to avoid that sudo commands in the script get stuck awaiting the password.
On Ubuntu 16, there is a simpler way: just add the user to the sudo group, like this:
sudo usermod -aG sudo *username*
From then on, it should work like a charm.
Note:
This works only on the condition that the following line is in file /etc/sudoers:
%sudo ALL=NOPASSWD: ALL
(such line gives passwordless sudo privileges at group level, in this case to the sudo group)
(if this line is not present and you want to add it, make sure you use visudo)
Simply, in order to execute commands as root you must use su (even sudo uses su)
As long as you execute sudo ./script2.sh successfully just instead :
sudo su
"#" //commands as root here
"#" exit
//commands as use here
you can make it a shell function with the name sudo, but no other better way i think,however it's the case with scripts inti,rc android ..etc
must be tidy ;)
however this requires you to put NOPASSWD: su wich is totaly secure indeed
any way here just lacks POISX permissions principle which is filtering so dont enable something to all users or vice versa
simply, call sudo as much as you want with no additional thing then:
chown root script.sh
chmod 0755 script.sh
chgrp sudo script.sh
"make root owner of .sh"
"make it read only and exec for others"
"and put it in sudo group"
of course under sudo
that's it
I seem to be stuck between an NFS limitation and a Cron limitation.
So I've got root cron (on RHEL5) running a shell script that, among other things, needs to rsync some files over an NFS mount. And the files on the NFS mount are owned by the apache user with mode 700, so only the apache user can run the rsync command -- running as root yields a permission error (NFS being a rare case, apparently, where the root user is not all-powerful?)
When I just want to run the rsync by hand, I can use "sudo -u apache rsync ..." But sudo no workie in cron -- it says "sudo: sorry, you must have a tty to run sudo".
I don't want to run the whole script as apache (i.e. from apache's crontab) because other parts of the script do require root -- it's just that one command that needs to run as apache. And I would really prefer not to change the mode on the files, as that will involve significant changes to other applications.
There's gotta be a way to accomplish "sudo -u apache" from cron??
thanks!
rob
su --shell=/bin/bash --session-command="/path/to/command -argument=something" username &
Works for me (CentOS)
Use su instead of sudo:
su -c "rsync ..." apache
By default on RHEL, sudo isn't allowed for processes without a terminal (tty). That's set in /etc/sudoers.
You can allow tty-less sudo for particular users with these instructions:
https://serverfault.com/questions/111064/sudoers-how-to-disable-requiretty-per-user
If you want to permanently enable you to fiddle around as apache:
chsh apache
this allows you to change the shell for the user
place it in /etc/crontab and specify apache instead of root in the user field