Checking for root user in sh and bash [duplicate]
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How to stop a script from running if it's not root (and echo “Not running as root! Exiting…â€)
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I am attempting to write a script that automates the installation of ports/packages on new FreeBSD installs. To do this, the user who executes the script must be root.
The system is "supposed" to be virgin meaning bash and sudo may or may not be installed; so I am trying to account for it. To do this, I am checking if the user ID equals 0.
The problem is, between bash and sh, the environment variables are different:
- bash -> $EUID (all caps)
- sh -> $euid (all lower)
Is there a different way other than the environment variable to check for root user or should I just adjust the checking of the user based on environment?
bash freebsd root bourne-shell
asked Mar 5 at 14:43
Allan
3742516
marked as duplicate by Kusalananda bash
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Mar 5 at 15:27
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
add a comment |Â
up vote
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This question already has an answer here:
How to stop a script from running if it's not root (and echo “Not running as root! Exiting…â€)
4 answers
I am attempting to write a script that automates the installation of ports/packages on new FreeBSD installs. To do this, the user who executes the script must be root.
The system is "supposed" to be virgin meaning bash and sudo may or may not be installed; so I am trying to account for it. To do this, I am checking if the user ID equals 0.
The problem is, between bash and sh, the environment variables are different:
- bash -> $EUID (all caps)
- sh -> $euid (all lower)
Is there a different way other than the environment variable to check for root user or should I just adjust the checking of the user based on environment?
bash freebsd root bourne-shell
asked Mar 5 at 14:43
Allan
3742516
marked as duplicate by Kusalananda bash
Users with the  bash badge can single-handedly close bash questions as duplicates and reopen them as needed.
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Mar 5 at 15:27
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
shon FreeBSD is the Almquist shell, not the Bourne shell. And theeuidshell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.
– JdeBP
Mar 5 at 15:07
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
You may think that you are runningsh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable.rootdoes not have the Almquist shell as its login shell, note.
– JdeBP
Mar 5 at 15:38
shon FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.
– Allan
Mar 5 at 15:55
1
No, they are not contradictory at all.roothas the TENEX C shell as its login shell, and that does not contradictshbeing the Almquist shell at all. As I said, you think that you are runningsh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell,root's login shell, clearly tells us.
– JdeBP
Mar 6 at 6:47
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
This question already has an answer here:
How to stop a script from running if it's not root (and echo “Not running as root! Exiting…â€)
4 answers
I am attempting to write a script that automates the installation of ports/packages on new FreeBSD installs. To do this, the user who executes the script must be root.
The system is "supposed" to be virgin meaning bash and sudo may or may not be installed; so I am trying to account for it. To do this, I am checking if the user ID equals 0.
The problem is, between bash and sh, the environment variables are different:
- bash -> $EUID (all caps)
- sh -> $euid (all lower)
Is there a different way other than the environment variable to check for root user or should I just adjust the checking of the user based on environment?
bash freebsd root bourne-shell
asked Mar 5 at 14:43
Allan
3742516
This question already has an answer here:
How to stop a script from running if it's not root (and echo “Not running as root! Exiting…â€)
4 answers
I am attempting to write a script that automates the installation of ports/packages on new FreeBSD installs. To do this, the user who executes the script must be root.
The system is "supposed" to be virgin meaning bash and sudo may or may not be installed; so I am trying to account for it. To do this, I am checking if the user ID equals 0.
The problem is, between bash and sh, the environment variables are different:
- bash -> $EUID (all caps)
- sh -> $euid (all lower)
Is there a different way other than the environment variable to check for root user or should I just adjust the checking of the user based on environment?
This question already has an answer here:
How to stop a script from running if it's not root (and echo “Not running as root! Exiting…â€)
4 answers
bash freebsd root bourne-shell
asked Mar 5 at 14:43
Allan
3742516
edited Mar 5 at 15:24
asked Mar 5 at 14:43
Allan
3742516
asked Mar 5 at 14:43
Allan
3742516
asked Mar 5 at 14:43
Allan
3742516
3742516
marked as duplicate by Kusalananda bash
Users with the  bash badge can single-handedly close bash questions as duplicates and reopen them as needed.
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Mar 5 at 15:27
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
marked as duplicate by Kusalananda bash
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Mar 5 at 15:27
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
shon FreeBSD is the Almquist shell, not the Bourne shell. And theeuidshell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.
– JdeBP
Mar 5 at 15:07
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
You may think that you are runningsh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable.rootdoes not have the Almquist shell as its login shell, note.
– JdeBP
Mar 5 at 15:38
shon FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.
– Allan
Mar 5 at 15:55
1
No, they are not contradictory at all.roothas the TENEX C shell as its login shell, and that does not contradictshbeing the Almquist shell at all. As I said, you think that you are runningsh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell,root's login shell, clearly tells us.
– JdeBP
Mar 6 at 6:47
add a comment |Â
shon FreeBSD is the Almquist shell, not the Bourne shell. And theeuidshell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.
– JdeBP
Mar 5 at 15:07
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
You may think that you are runningsh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable.rootdoes not have the Almquist shell as its login shell, note.
– JdeBP
Mar 5 at 15:38
shon FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.
– Allan
Mar 5 at 15:55
1
No, they are not contradictory at all.roothas the TENEX C shell as its login shell, and that does not contradictshbeing the Almquist shell at all. As I said, you think that you are runningsh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell,root's login shell, clearly tells us.
– JdeBP
Mar 6 at 6:47
sh on FreeBSD is the Almquist shell, not the Bourne shell. And the euid shell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.– JdeBP
Mar 5 at 15:07
sh on FreeBSD is the Almquist shell, not the Bourne shell. And the euid shell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.– JdeBP
Mar 5 at 15:07
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
You may think that you are running
sh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable. root does not have the Almquist shell as its login shell, note.– JdeBP
Mar 5 at 15:38
You may think that you are running
sh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable. root does not have the Almquist shell as its login shell, note.– JdeBP
Mar 5 at 15:38
sh on FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.– Allan
Mar 5 at 15:55
sh on FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.– Allan
Mar 5 at 15:55
1
1
No, they are not contradictory at all.
root has the TENEX C shell as its login shell, and that does not contradict sh being the Almquist shell at all. As I said, you think that you are running sh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell, root's login shell, clearly tells us.– JdeBP
Mar 6 at 6:47
No, they are not contradictory at all.
root has the TENEX C shell as its login shell, and that does not contradict sh being the Almquist shell at all. As I said, you think that you are running sh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell, root's login shell, clearly tells us.– JdeBP
Mar 6 at 6:47
add a comment |Â
2 Answers
2
active
oldest
votes
up vote
4
down vote
accepted
I would check the value of id -u, which is specified to:
Output only the effective user ID, using the format "%un".
Perhaps like this:
if [ $(id -u) -eq 0 ]
then
: root
else
: not root
fi
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
add a comment |Â
up vote
0
down vote
It looks like you can simply test for $UID == 0 in both shells. Since the name root isn't the important part, and you can actually have a user named root with a non-zero UID, or a UID 0 account named something other than root, this might be a better way of checking that the script is running as a privileged user.
answered Mar 5 at 14:46
John
11.2k11630
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
Shell variables can have any value and can not be trusted. I could easily setUID=0in my personal shell init files, for example. Useidinstead.
– Kusalananda
Mar 5 at 14:53
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
accepted
I would check the value of id -u, which is specified to:
Output only the effective user ID, using the format "%un".
Perhaps like this:
if [ $(id -u) -eq 0 ]
then
: root
else
: not root
fi
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
add a comment |Â
up vote
4
down vote
accepted
I would check the value of id -u, which is specified to:
Output only the effective user ID, using the format "%un".
Perhaps like this:
if [ $(id -u) -eq 0 ]
then
: root
else
: not root
fi
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
add a comment |Â
up vote
4
down vote
accepted
up vote
4
down vote
accepted
I would check the value of id -u, which is specified to:
Output only the effective user ID, using the format "%un".
Perhaps like this:
if [ $(id -u) -eq 0 ]
then
: root
else
: not root
fi
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
I would check the value of id -u, which is specified to:
Output only the effective user ID, using the format "%un".
Perhaps like this:
if [ $(id -u) -eq 0 ]
then
: root
else
: not root
fi
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
answered Mar 5 at 14:53
Jeff Schaller
31.2k846105
31.2k846105
add a comment |Â
add a comment |Â
up vote
0
down vote
It looks like you can simply test for $UID == 0 in both shells. Since the name root isn't the important part, and you can actually have a user named root with a non-zero UID, or a UID 0 account named something other than root, this might be a better way of checking that the script is running as a privileged user.
answered Mar 5 at 14:46
John
11.2k11630
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
Shell variables can have any value and can not be trusted. I could easily setUID=0in my personal shell init files, for example. Useidinstead.
– Kusalananda
Mar 5 at 14:53
add a comment |Â
up vote
0
down vote
It looks like you can simply test for $UID == 0 in both shells. Since the name root isn't the important part, and you can actually have a user named root with a non-zero UID, or a UID 0 account named something other than root, this might be a better way of checking that the script is running as a privileged user.
answered Mar 5 at 14:46
John
11.2k11630
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
Shell variables can have any value and can not be trusted. I could easily setUID=0in my personal shell init files, for example. Useidinstead.
– Kusalananda
Mar 5 at 14:53
add a comment |Â
up vote
0
down vote
up vote
0
down vote
It looks like you can simply test for $UID == 0 in both shells. Since the name root isn't the important part, and you can actually have a user named root with a non-zero UID, or a UID 0 account named something other than root, this might be a better way of checking that the script is running as a privileged user.
answered Mar 5 at 14:46
John
11.2k11630
It looks like you can simply test for $UID == 0 in both shells. Since the name root isn't the important part, and you can actually have a user named root with a non-zero UID, or a UID 0 account named something other than root, this might be a better way of checking that the script is running as a privileged user.
answered Mar 5 at 14:46
John
11.2k11630
answered Mar 5 at 14:46
John
11.2k11630
answered Mar 5 at 14:46
John
11.2k11630
answered Mar 5 at 14:46
John
11.2k11630
11.2k11630
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
Shell variables can have any value and can not be trusted. I could easily setUID=0in my personal shell init files, for example. Useidinstead.
– Kusalananda
Mar 5 at 14:53
add a comment |Â
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
Shell variables can have any value and can not be trusted. I could easily setUID=0in my personal shell init files, for example. Useidinstead.
– Kusalananda
Mar 5 at 14:53
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
I probably didn't explain it correctly so I'll fix. I'm already checking for a a user ID = 0. The problem is one shell the env. variable is in all caps and the other environment is all lower.
– Allan
Mar 5 at 14:49
1
1
Shell variables can have any value and can not be trusted. I could easily set
UID=0 in my personal shell init files, for example. Use id instead.– Kusalananda
Mar 5 at 14:53
Shell variables can have any value and can not be trusted. I could easily set
UID=0 in my personal shell init files, for example. Use id instead.– Kusalananda
Mar 5 at 14:53
add a comment |Â
shon FreeBSD is the Almquist shell, not the Bourne shell. And theeuidshell variable that you describe is set by neither the Almquist shell nor the Bourne shell. It is set by the TENEX C shell. You will find it quite difficult to write a script that works on both the Almquist/Bourne Again/Korn/Z shells and the C shell.– JdeBP
Mar 5 at 15:07
@JdeBP - I learned something new re: Almquist. As for the the varialbes, I am on a virgin FreeBSD install right now (save for bash) and those are the env. variables that are set; bash has all uppers and sh has all lowers. My goal is to write something that's compatible in sh and bash only.
– Allan
Mar 5 at 15:26
You may think that you are running
sh. But by the presence of that variable you are clearly not. The Almquist shell, as I said, does not set such a variable.rootdoes not have the Almquist shell as its login shell, note.– JdeBP
Mar 5 at 15:38
shon FreeBSD is the Almquist shell and root does not have the Almquist shell as its login. These statements are contradictory. Either root has the Almquist shell in FreeBSD and I'm running it or FreeBSD doesn't use the Almquist shell. I am running FreeBSD and logged in as root using the default sh shell.– Allan
Mar 5 at 15:55
1
No, they are not contradictory at all.
roothas the TENEX C shell as its login shell, and that does not contradictshbeing the Almquist shell at all. As I said, you think that you are runningsh. But in fact that is not what you are doing, as the presence of a shell variable set by the TENEX C shell,root's login shell, clearly tells us.– JdeBP
Mar 6 at 6:47