Cannot change the environment variable











up vote
4
down vote

favorite












WHAT I AM USING




  • zsh

  • MacOS Mojave 14.10


WHAT I WANT TO DO



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

newvalue


WHAT IS HAPPENING



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

myusername


WHAT I TRIED



Tried to set USERNAME in .bashrc, .zshrc, .profile and nothing changes...



Tried to unset and reset and nothing changes...






osx zsh environment-variables







share|improve this question









New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • This variable is readonly and you can change it by switching user
    – Romeo Ninov
    yesterday










  • The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
    – Riccardo Persiani
    yesterday










  • Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
    – telcoM
    yesterday






  • 1




    This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
    – Kusalananda
    yesterday






  • 2




    what does typeset -p USERNAME say?
    – mosvy
    yesterday















up vote
4
down vote

favorite












WHAT I AM USING




  • zsh

  • MacOS Mojave 14.10


WHAT I WANT TO DO



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

newvalue


WHAT IS HAPPENING



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

myusername


WHAT I TRIED



Tried to set USERNAME in .bashrc, .zshrc, .profile and nothing changes...



Tried to unset and reset and nothing changes...






osx zsh environment-variables







share|improve this question









New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • This variable is readonly and you can change it by switching user
    – Romeo Ninov
    yesterday










  • The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
    – Riccardo Persiani
    yesterday










  • Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
    – telcoM
    yesterday






  • 1




    This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
    – Kusalananda
    yesterday






  • 2




    what does typeset -p USERNAME say?
    – mosvy
    yesterday













up vote
4
down vote

favorite









up vote
4
down vote

favorite











WHAT I AM USING




  • zsh

  • MacOS Mojave 14.10


WHAT I WANT TO DO



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

newvalue


WHAT IS HAPPENING



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

myusername


WHAT I TRIED



Tried to set USERNAME in .bashrc, .zshrc, .profile and nothing changes...



Tried to unset and reset and nothing changes...






osx zsh environment-variables







share|improve this question









New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











WHAT I AM USING




  • zsh

  • MacOS Mojave 14.10


WHAT I WANT TO DO



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

newvalue


WHAT IS HAPPENING



$ echo $USERNAME

myusername

$ export USERNAME=newvalue

$ echo $USERNAME

myusername


WHAT I TRIED



Tried to set USERNAME in .bashrc, .zshrc, .profile and nothing changes...



Tried to unset and reset and nothing changes...






osx zsh environment-variables




osx zsh environment-variables






share|improve this question









New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited yesterday





















New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked yesterday









Riccardo Persiani

1235




1235




New contributor




Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Riccardo Persiani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • This variable is readonly and you can change it by switching user
    – Romeo Ninov
    yesterday










  • The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
    – Riccardo Persiani
    yesterday










  • Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
    – telcoM
    yesterday






  • 1




    This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
    – Kusalananda
    yesterday






  • 2




    what does typeset -p USERNAME say?
    – mosvy
    yesterday


















  • This variable is readonly and you can change it by switching user
    – Romeo Ninov
    yesterday










  • The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
    – Riccardo Persiani
    yesterday










  • Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
    – telcoM
    yesterday






  • 1




    This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
    – Kusalananda
    yesterday






  • 2




    what does typeset -p USERNAME say?
    – mosvy
    yesterday
















This variable is readonly and you can change it by switching user
– Romeo Ninov
yesterday




This variable is readonly and you can change it by switching user
– Romeo Ninov
yesterday












The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
– Riccardo Persiani
yesterday




The weird thing is I am quite sure that I was able to change it, then I had probably messed up with something..
– Riccardo Persiani
yesterday












Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
– telcoM
yesterday




Do you see readonly USERNAME or declare -r USERNAME anywhere? Either of those would mark a variable as read-only.
– telcoM
yesterday




1




1




This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
– Kusalananda
yesterday




This is not a variable that is set by default on macOS. Are you setting it yourself somewhere?
– Kusalananda
yesterday




2




2




what does typeset -p USERNAME say?
– mosvy
yesterday




what does typeset -p USERNAME say?
– mosvy
yesterday










1 Answer
1






active

oldest

votes

















up vote
12
down vote



accepted










The USERNAME shell variable is special in the Z shell.



It is always the account name of the user ID of the shell process.



You won't observe the behaviour that you observed in the Almquist, Watanabe, Korn, or Bourne Again shells. This variable is just an ordinary shell variable, that starts out unset, as far as they are concerned. Here's the 93 Korn shell, for example:



$ echo $USERNAME



$ USERNAME=wibble

$ echo $USERNAME

wibble

$


In the Z shell it starts out as the account name of the UID of the shell process. An attempt to set it will attempt to change that UID. This of course fails if you are not the superuser and leaves the variable back as it was before.



If you had run the Z shell as the superuser, however, you would have seen both the USERNAME shell variable and your shell process's user ID change.


root # echo $USERNAME

root

root # USERNAME=JdeBP

JdeBP %


Further reading




  • Paul Falstad et al. (2015-12-02). "Parameters Set By The Shell". Z Shell Manual. 5.2.






share|improve this answer





















  • Running as a superuser I am able to change the variable. Thank you
    – Riccardo Persiani
    yesterday








  • 2




    @RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
    – Kusalananda
    yesterday










  • I agree. However, I also can change it, simply switching from zsh to bash.
    – Riccardo Persiani
    yesterday






  • 1




    Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
    – Stéphane Chazelas
    yesterday











Your Answer








StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});






Riccardo Persiani is a new contributor. Be nice, and check out our Code of Conduct.










 

draft saved


draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f483469%2fcannot-change-the-environment-variable%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
12
down vote



accepted










The USERNAME shell variable is special in the Z shell.



It is always the account name of the user ID of the shell process.



You won't observe the behaviour that you observed in the Almquist, Watanabe, Korn, or Bourne Again shells. This variable is just an ordinary shell variable, that starts out unset, as far as they are concerned. Here's the 93 Korn shell, for example:



$ echo $USERNAME



$ USERNAME=wibble

$ echo $USERNAME

wibble

$


In the Z shell it starts out as the account name of the UID of the shell process. An attempt to set it will attempt to change that UID. This of course fails if you are not the superuser and leaves the variable back as it was before.



If you had run the Z shell as the superuser, however, you would have seen both the USERNAME shell variable and your shell process's user ID change.


root # echo $USERNAME

root

root # USERNAME=JdeBP

JdeBP %


Further reading




  • Paul Falstad et al. (2015-12-02). "Parameters Set By The Shell". Z Shell Manual. 5.2.






share|improve this answer





















  • Running as a superuser I am able to change the variable. Thank you
    – Riccardo Persiani
    yesterday








  • 2




    @RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
    – Kusalananda
    yesterday










  • I agree. However, I also can change it, simply switching from zsh to bash.
    – Riccardo Persiani
    yesterday






  • 1




    Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
    – Stéphane Chazelas
    yesterday















up vote
12
down vote



accepted










The USERNAME shell variable is special in the Z shell.



It is always the account name of the user ID of the shell process.



You won't observe the behaviour that you observed in the Almquist, Watanabe, Korn, or Bourne Again shells. This variable is just an ordinary shell variable, that starts out unset, as far as they are concerned. Here's the 93 Korn shell, for example:



$ echo $USERNAME



$ USERNAME=wibble

$ echo $USERNAME

wibble

$


In the Z shell it starts out as the account name of the UID of the shell process. An attempt to set it will attempt to change that UID. This of course fails if you are not the superuser and leaves the variable back as it was before.



If you had run the Z shell as the superuser, however, you would have seen both the USERNAME shell variable and your shell process's user ID change.


root # echo $USERNAME

root

root # USERNAME=JdeBP

JdeBP %


Further reading




  • Paul Falstad et al. (2015-12-02). "Parameters Set By The Shell". Z Shell Manual. 5.2.






share|improve this answer





















  • Running as a superuser I am able to change the variable. Thank you
    – Riccardo Persiani
    yesterday








  • 2




    @RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
    – Kusalananda
    yesterday










  • I agree. However, I also can change it, simply switching from zsh to bash.
    – Riccardo Persiani
    yesterday






  • 1




    Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
    – Stéphane Chazelas
    yesterday













up vote
12
down vote



accepted







up vote
12
down vote



accepted






The USERNAME shell variable is special in the Z shell.



It is always the account name of the user ID of the shell process.



You won't observe the behaviour that you observed in the Almquist, Watanabe, Korn, or Bourne Again shells. This variable is just an ordinary shell variable, that starts out unset, as far as they are concerned. Here's the 93 Korn shell, for example:



$ echo $USERNAME



$ USERNAME=wibble

$ echo $USERNAME

wibble

$


In the Z shell it starts out as the account name of the UID of the shell process. An attempt to set it will attempt to change that UID. This of course fails if you are not the superuser and leaves the variable back as it was before.



If you had run the Z shell as the superuser, however, you would have seen both the USERNAME shell variable and your shell process's user ID change.


root # echo $USERNAME

root

root # USERNAME=JdeBP

JdeBP %


Further reading




  • Paul Falstad et al. (2015-12-02). "Parameters Set By The Shell". Z Shell Manual. 5.2.






share|improve this answer












The USERNAME shell variable is special in the Z shell.



It is always the account name of the user ID of the shell process.



You won't observe the behaviour that you observed in the Almquist, Watanabe, Korn, or Bourne Again shells. This variable is just an ordinary shell variable, that starts out unset, as far as they are concerned. Here's the 93 Korn shell, for example:



$ echo $USERNAME



$ USERNAME=wibble

$ echo $USERNAME

wibble

$


In the Z shell it starts out as the account name of the UID of the shell process. An attempt to set it will attempt to change that UID. This of course fails if you are not the superuser and leaves the variable back as it was before.



If you had run the Z shell as the superuser, however, you would have seen both the USERNAME shell variable and your shell process's user ID change.


root # echo $USERNAME

root

root # USERNAME=JdeBP

JdeBP %


Further reading




  • Paul Falstad et al. (2015-12-02). "Parameters Set By The Shell". Z Shell Manual. 5.2.







share|improve this answer












share|improve this answer



share|improve this answer










answered yesterday









JdeBP

31.7k467148




31.7k467148












  • Running as a superuser I am able to change the variable. Thank you
    – Riccardo Persiani
    yesterday








  • 2




    @RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
    – Kusalananda
    yesterday










  • I agree. However, I also can change it, simply switching from zsh to bash.
    – Riccardo Persiani
    yesterday






  • 1




    Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
    – Stéphane Chazelas
    yesterday


















  • Running as a superuser I am able to change the variable. Thank you
    – Riccardo Persiani
    yesterday








  • 2




    @RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
    – Kusalananda
    yesterday










  • I agree. However, I also can change it, simply switching from zsh to bash.
    – Riccardo Persiani
    yesterday






  • 1




    Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
    – Stéphane Chazelas
    yesterday
















Running as a superuser I am able to change the variable. Thank you
– Riccardo Persiani
yesterday






Running as a superuser I am able to change the variable. Thank you
– Riccardo Persiani
yesterday






2




2




@RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
– Kusalananda
yesterday




@RiccardoPersiani Ummm... switching to root is not a "solution". Why do you need to change the value of this variable?
– Kusalananda
yesterday












I agree. However, I also can change it, simply switching from zsh to bash.
– Riccardo Persiani
yesterday




I agree. However, I also can change it, simply switching from zsh to bash.
– Riccardo Persiani
yesterday




1




1




Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
– Stéphane Chazelas
yesterday




Note that there can be more than one user name for a user id, zsh reports the one returned by getpwuid() so an arbitrary one (one could argue it should use logname() instead). Changing $USERNAME does a setuid(), but also setgid()/setgroups() with the groups mentioned in the user database as when you log in as that user name, that's different from setting $UID or $EUID for instance. So by doing a USERNAME=$USERNAME you might very well change the list of groups of the process if there are several usernames for the current uid with different group membership.
– Stéphane Chazelas
yesterday










Riccardo Persiani is a new contributor. Be nice, and check out our Code of Conduct.










 

draft saved


draft discarded


















Riccardo Persiani is a new contributor. Be nice, and check out our Code of Conduct.













Riccardo Persiani is a new contributor. Be nice, and check out our Code of Conduct.












Riccardo Persiani is a new contributor. Be nice, and check out our Code of Conduct.















 


draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f483469%2fcannot-change-the-environment-variable%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







-

Popular posts from this blog

Accessing regular linux commands in Huawei's Dopra Linux

Image
4 Backstory: I have a Huawei HG8245 router in my house and I want to change the default username/password. I've tried following this guide but the config file always gets reset. My ISP isn't helping either so I'm looking for other ways to accomplish this. The router has telnet access so this seems like a way to change the credentials. The first shell I gain access to looks like this: WAP> Pressing "?" gives me a list of available commands which I've pasted here, the two interesting ones are "su" and "shell". I can't seem to get su access, even after logging in as root (challenge password prompt, and then nothing happens), but shell gives me a proper linux shell. WAP>shell BusyBox v1.18.4 (2017-12-26 17:06:34 CST) built-in shell (ash) Enter 'hel...
Read more

Can't connect RFCOMM socket: Host is down

Image
up vote 3 down vote favorite I have bluez 5.4.3 and I am attempting to communicate with a ble device through minicom. These two deceives (my computer and a bluno nano) are alreadt paired and this has been my method so far. #bluetoothctl # pair xx:xx:xx:xx:xx:xx # exit Everything is working well so far then... #sudo rfcomm connect /dev/rfcomm0 xx:xx:xx:xx:xx:xx 1 & [1] 3665 Can't connect RFCOMM socket: Host is down Does anyone know how to resolve this issue? Any help would be very much appreciated. bluetooth bluez share | improve this question asked Feb 9 '17 at 18:46 Brandon Knape 46 2 ...
Read more

Kernel panic - not syncing: Fatal Exception in Interrupt

Image
0 Every day this error occured on my pc, kernel panic error on interrupt, what will be the problem? linux-mint share asked 6 mins ago Vinod Selvin Vinod Selvin 1 1 New contributor Vinod Selvin is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct. add a comment ...
Read more