I'm working with a support member for a product, and he insists that I need to be root to install a series of patches, and that sudo won't work; he doesn't provide a reason but seems very firm in his beliefs. Browsing Superuser I can't determine any possible reason for this being the case, and in confirmation, when I run:
sudo -l
I get:
...
User [MY USERNAME] may run the following commands on this host:
(ALL) ALL
Getting access from the Linux/server team to actually be root is not an imediate process as I understand, so I'd prefer to install them myself.
Is there any practical reason whatsoever why sudo would behave differently than root for installing software on a server?
Answer
It strongly depends on how you call your program with sudo or su.
E.g. on the system on which I am in this moment:
.bashrc
COMMAND $HOME $USER Env. $PATH
1. sudo -i (root) root root [1]
2. sudo -s (USER) root USER /home/${USER}/bin:[1]
3. sudo /bin/bash (USER) root USER /home/${USER}/bin:[1]
4. sudo su (root) root USER [1]:/usr/games:/usr/local/games
5. sudo su - (root) root root [1]
Where [1]=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
Env=Environment variables are reset for 1 and 5, taken from $USER in 2,3,4.
So a script, or a program that is launched with a different option can see different $PATH, $HOME, its shell can read different .bashrc,.profile and Environment variables. It reads the file related with the $HOME. Each user can modify his environment in a different way (variables, $PATH, .bashrc, .profile, .bash_profile, alias...). In particular a user can have a different order of the directories in his $PATH and, as a consequence, a script can execute a command e.g. in /home/$USER/bin instead then the one in the path expected from root.
You can run the program under sudo -i as you were logged as root with su -, but you can have different behaviour if you run it with sudo MyCommand or with su -c MyCommand.
From man su:
In the description part:
The current environment is passed to the new shell. The value of $PATH is reset to /bin:/usr/bin for normal users, or /sbin:/bin:/usr/sbin:/usr/bin for the superuser
...
In the options part:
-, -l, --login
Provide an environment similar to what the user would expect had the user logged in directly.
From man sudo
-i, --login
Run the shell specified by the target user's password database entry as a login shell. This means that login-specific resource files such as .profile or .login will be read by the shell. If a command is specified, it is passed to the shell for execution via the shell's -c option. If no command is specified, an interactive shell is executed.sudoattempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. The Command Environment section in the sudoers(5) manual documents how the -i option affects the environment in which a command is run when the sudoers policy is in use.
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