Execute a shell script in current shell with sudo permission

Question

For executing a shell script in current shell  we need to use a period   or a source command  But why does it not work with a sudo permission   I have a script with execute permission called setup sh  When I use a period  I get this     sudo     setup sh  sudo     command not found   The source command also produces a similar error  Am I missing out something  What should I do to run the script with sudo permission in the same shell   Thanks in advance

User · Answer

I think you are confused about the difference between sourcing and executing a script.

Executing a script means creating a new process, and running the program. The program can be a shell script, or any other type of program. As it is a sub process, any environmental variables changed in the program will not affect the shell.

Sourcing a script can only be used with a bash script (if you are running bash). It effectively types the commands in as if you did them. This is useful as it lets a script change environmental variables in the shell.

Running a script is simple, you just type in the path to the script. . is the current directory. So ./script.sh will execute the file script.sh in the current directory. If the command is a single file (eg script.sh), it will check all the folders in the PATH variable to find the script. Note that the current directory isn't in PATH, so you can't execute a file script.sh in the current directory by running script.sh, you need to run ./script.sh (unless the current directory is in the PATH, eg you can run ls while in the /bin dir).

Sourcing a script doesn't use the PATH, and just searches for the path. Note that source isn't a program - otherwise it wouldn't be able to change environmental variables in the current shell. It is actually a bash built in command. Search /bin and /usr/bin - you won't find a source program there. So to source a file script.sh in the current directory, you just use source script.sh.

How does sudo interact with this? Well sudo takes a program, and executes it as root. Eg sudo ./script.sh executes script.sh in a sub process but running as root.

What does sudo source ./script.sh do however? Remember source isn't a program (rather a shell builtin)? Sudo expects a program name though, so it searches for a program named source. It doesn't find one, and so fails. It isn't possible to source a file running as root, without creating a new subprocess, as you cannot change the runner of a program (in this case, bash) after it has started.

I'm not sure what you actually wanted, but hopefully this will clear it up for you.

Here is a concrete example. Make the file script.sh in your current directory with the contents:

#!/bin/bash    
export NEW_VAR="hello"
whoami
echo "Some text"

Make it executable with chmod +x script.sh.

Now observe what happens with bash:

> ./script.sh
david
Some text
> echo $NEW_VAR

> sudo ./script.sh
root
Some text
> echo $NEW_VAR

> source script.sh
david
Some text
> echo $NEW_VAR
hello
> sudo source script.sh
sudo: source: command not found

User · Answer

If you really want to  ExecuteCall a shell script in current shell with sudo permission  you can use exec to        replace the shell with a given program  executing it  not as new process    I insist on replacing  execute  with  call  because the former has a meaning that includes creating a new process and ID  where the latter is ambiguous and leaves room for creativity  of which I am full    Consider this test case and look closely at pid 1337      Don t worry  the content of this script is cat ed below     test sh -o foo -p bar  User ubuntu is running     PID TT       USER     COMMAND  775 pts 1    ubuntu   -bash 1408 pts 1    ubuntu       bash   test sh -o foo -p bar 1411 pts 1    ubuntu           ps -t  dev pts 1 -fo pid tty user args  User root is running     PID TT       USER     COMMAND  775 pts 1    ubuntu   -bash 1337 pts 1    root         sudo   test sh -o foo -p bar 1412 pts 1    root             bash   test sh -o foo -p bar 1415 pts 1    root                 ps -t  dev pts 1 -fo pid tty user args  Take  exec  out of the command and this script would get cat-ed twice   Try it       usr bin env bash  echo  echo  User   whoami  is running     ps -t   tty  -fo pid tty user args  if     EUID  gt  0     then       exec replaces the current process effectively ending execution so no exit is needed      exec sudo   0       fi  echo  echo  Take  exec  out of the command and this script would get cat-ed twice   Try it     echo cat  0   Here is another test using sudo -s    ps -fo pid tty user args    test2 sh   PID TT       USER     COMMAND 10775 pts 1    ubuntu   -bash 11496 pts 1    ubuntu       ps -fo pid tty user args  User ubuntu is running      PID TT       USER     COMMAND 10775 pts 1    ubuntu   -bash 11497 pts 1    ubuntu       bash   test2 sh 11500 pts 1    ubuntu           ps -fo pid tty user args  User root is running      PID TT       USER     COMMAND 11497 pts 1    root     sudo -s 11501 pts 1    root          bin bash 11503 pts 1    root             ps -fo pid tty user args    cat test2 src echo  echo  User   whoami  is running     ps -fo pid tty user args    cat test2 sh    usr bin env bash  source test2 src  exec sudo -s  lt  test2 src   And a simpler test using sudo -s      exec sh bash s PID 25194    user ID 7809 systemd 1 ---bash 23064 ---bash 25194 ---pstree 25196   Finally    bash s PID 25199    user ID 0 systemd 1 ---bash 23064 ---sudo 25194 ---bash 25199 ---pstree 25201     cat exec sh    usr bin env bash  pid    id   id -u  echo  bash s PID  pid    user ID  id  pstree -ps  pid    the quoted EOF is important to prevent shell expansion of the      exec sudo -s  lt  lt EOF echo echo  Finally     echo  bash s PID         user ID    id -u   pstree -ps  pid EOF

User · Answer

Easiest method is to type   sudo  bin sh example sh

User · Answer

What you are trying to do is impossible  your current shell is running under your regular user ID  i e  without root the access sudo would give you   and there is no way to grant it root access  What sudo does is create a new  sub process that runs as root  The subprocess could be just a regular program  e g  sudo cp     runs the cp program in a root process  or it could be a root subshell  but it cannot be the current shell    It s actually even more impossible than that  because the sudo command itself is executed as a subprocess of the current shell -- meaning that in a sense it s already too late for it to do anything in the  current shell   because that s not where it executes

User · Answer

The answers here explain why it happens but I thought I d add my simple way around the issue  First you can cat the file into a variable with sudo permissions  Then you can evaluate the variable to execute the code in the file in your current shell   Here is an example of reading and executing an  env file  ex Docker     sensitive stuff   sudo cat   env    eval    sensitive stuff    echo  ADMIN PASSWORD

User · Answer

Basically sudo expects  an executable  command  to follow  amp  you are providing with a    Hence the error   Try this way   sudo setup sh

User · Answer

Even the first answer is absolutely brilliant  you probably want to only run script under sudo   You have to specify the absolute path like   sudo  home user example sh sudo   example sh    both are working   THIS WONT WORK   sudo  bin sh example sh sudo example sh   It will always return  sudo  bin sh  command not found sudo  example sh  command not found

User · Answer

I m not sure if this breaks any rules but   sudo bash script sh   seems to work for me

[linux] Execute a shell script in current shell with sudo permission

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