Serial Port configuration in RHEL
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NEVER EVER use root like that. All the more when developing. It's bad practice and doing so you're opening a gaping security hole.
Add your normal user to the
dialoutgroup and be done with it. -
@Nimika
Hi
Any user can be granted access to /dev/X devices.
Often it is done via the dialout group as its already assigned to serial devices such as ttyS0 and
any user that is member of that group can use it.
so often
sudo adduser TheUserName dialout
and and reboot is all that is needed.
Adding user to group might have slightly different syntax on RH but concept and rights are 100% the same.:)
http://websistent.com/fix-serial-port-permission-denied-errors-linux/ -
@Nimika
Hi
Any user can be granted access to /dev/X devices.
Often it is done via the dialout group as its already assigned to serial devices such as ttyS0 and
any user that is member of that group can use it.
so often
sudo adduser TheUserName dialout
and and reboot is all that is needed.
Adding user to group might have slightly different syntax on RH but concept and rights are 100% the same.:)
http://websistent.com/fix-serial-port-permission-denied-errors-linux/ -
@Nimika
Hi
Any user can be granted access to /dev/X devices.
Often it is done via the dialout group as its already assigned to serial devices such as ttyS0 and
any user that is member of that group can use it.
so often
sudo adduser TheUserName dialout
and and reboot is all that is needed.
Adding user to group might have slightly different syntax on RH but concept and rights are 100% the same.:)
http://websistent.com/fix-serial-port-permission-denied-errors-linux/ -
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@jsulm Thank you!!
But still in my case maybe RHEL is not allowing any other user to add in dialout group.@Nimika said in Serial Port configuration in RHEL:
RHEL is not allowing any other user to add in dialout group.
cant you just use sudo in front?
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@jsulm Thank you!!
But still in my case maybe RHEL is not allowing any other user to add in dialout group.@Nimika RHEL works like any other Linux distribution. To add a user to a group you need to be root. You can either login as root, or just enter su in a terminal window enter your root password and then add the user to the group. su is used to become root in a shell (you need root password).
@mrjj I think on RHEL sudo is usually not used, so sudo will probably not work (as far as I know, I could be wrong as I use Ubuntu). -
@Nimika RHEL works like any other Linux distribution. To add a user to a group you need to be root. You can either login as root, or just enter su in a terminal window enter your root password and then add the user to the group. su is used to become root in a shell (you need root password).
@mrjj I think on RHEL sudo is usually not used, so sudo will probably not work (as far as I know, I could be wrong as I use Ubuntu). -
@jsulm
Yeah I did all possibilities which I think can be done on RHEL.
By the way Thanks a lot for your all kind replies. :)@Nimika So, is your user now member of dialout group? You can check this executing "groups" command in a terminal (not as root but as the user who needs the access rights!). You can add a user to a group manually: open /etc/group file in an editor (as root), look for a line like "dialout:x:115:" and append user name at the end of that line.
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In addition to what my fellows already wrote, if you're not too found of manipulating your user setting with the command line, most of desktop environment (KDE, Gnome, etc.) provide user management software so you'll likely be able to add your user to the
dialoutgroup with them. They should ask for an admin password when required. -
@Nimika RHEL works like any other Linux distribution. To add a user to a group you need to be root. You can either login as root, or just enter su in a terminal window enter your root password and then add the user to the group. su is used to become root in a shell (you need root password).
@mrjj I think on RHEL sudo is usually not used, so sudo will probably not work (as far as I know, I could be wrong as I use Ubuntu).@jsulm
Oh, you are right. it might not be set up at all
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/2/html/Getting_Started_Guide/ch02s03.html
so su is the way to go. -
@Nimika So, is your user now member of dialout group? You can check this executing "groups" command in a terminal (not as root but as the user who needs the access rights!). You can add a user to a group manually: open /etc/group file in an editor (as root), look for a line like "dialout:x:115:" and append user name at the end of that line.
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@Nimika Sorry, I don't understand. To add a user manually you open /etc/group file in a editor (you need to be root to edit this file). Look for the group "dialout" and append the username at the end of the line containing the group, like:
dialout:x:124:myuserThis is how it works on UNIX/Linux since decades.
"it is showing that this user is already have the group" - what/who is showing this?So, here what you should do:
$ su ENTER YOUR ROOT PASSWORD $ vim /etc/group APPEND USERNAME AT THE END OF THEdialout LINE SAVE THE FILE CLOSE vimYou can use another editor instead of vim.
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@Nimika
HI
I think the champion means that many newer distros have also a GUI version
to change user / groups versus using the command line. :)
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@Nimika Then this user should now have access. The user needs to log out and log in again after adding him to a group.
Does it work now? -
Some admins do not like you to cross groups (Like US GOV admins). You can, however, get them to make a UDEV rule that will set the permissions when the port is found. This is especially useful if you need many users to access the port.
This is a more permanent solution than using rc.local to change port access modes as it will set the modes each time the port is plugged-in as well as when the computer is rebooted. Your admin should know how to do this. If you are the admin, there are plenty of technotes on adding rules to UDEV. You can even give the port a better, more consistent, name the ones the kernel provides as they can reorder at reboot, etc.
In
/etc/rules.d/my.rules/etc/udev/rules.dSUBSYSTEM=="tty", ENV{ID_PATH}=="pci-blah blah blah", MODE="0666", SYMLINK+="tty-my-device"
The "pci-blah blah blah" can be found using udevadm info /dev/tty<device>
Dave Fileccia
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Some admins do not like you to cross groups (Like US GOV admins). You can, however, get them to make a UDEV rule that will set the permissions when the port is found. This is especially useful if you need many users to access the port.
This is a more permanent solution than using rc.local to change port access modes as it will set the modes each time the port is plugged-in as well as when the computer is rebooted. Your admin should know how to do this. If you are the admin, there are plenty of technotes on adding rules to UDEV. You can even give the port a better, more consistent, name the ones the kernel provides as they can reorder at reboot, etc.
In
/etc/rules.d/my.rules/etc/udev/rules.dSUBSYSTEM=="tty", ENV{ID_PATH}=="pci-blah blah blah", MODE="0666", SYMLINK+="tty-my-device"
The "pci-blah blah blah" can be found using udevadm info /dev/tty<device>
@Buckwheat Sorry, it is /etc/udev/rules.d
