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0

I am aware of

/usr/bin/env -i /bin/bash --login --norc --noprofile

And indeed, If I run the above, and immediately after run printenv in the new shell session, I see that very few exported variables are defined:

% /usr/bin/env -i /bin/bash --login --norc --noprofile

bash-4.4$ printenv | /usr/bin/perl -lpe 's/=.*//'

PWD

SHLVL

_

bash-4.4$ 

But if instead I run set, I see a lot of variables:

bash-4.4$ set | /usr/bin/perl -lpe 's/=.*//'

BASH

BASHOPTS

BASH_ALIASES

BASH_ARGC

BASH_ARGV

BASH_CMDS

BASH_LINENO

BASH_SOURCE

BASH_VERSINFO

BASH_VERSION

COLUMNS

DIRSTACK

EUID

GROUPS

HISTFILE

HISTFILESIZE

HISTSIZE

HOSTNAME

HOSTTYPE

IFS

LINES

MACHTYPE

MAILCHECK

OPTERR

OPTIND

OSTYPE

PATH

PPID

PS1

PS2

PS4

PWD

SHELL

SHELLOPTS

SHLVL

TERM

UID

_

bash-4.4$ 

For the sake of this question, let me define a shell variable as being "indispensable" iff bash simply won't run unless this variable is present (as indicated by its showing up in set's output). For example, PPID appears to be indispensable. (bash emits an error if one tries to unset it.)

What is the easiest way to reduce the set of defined variables to hold only the indispensable ones?

shell environment-variables

share|improve this question

edited 34 mins ago

kjo

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Your question is too broad and would be impossible for anyone to completely answer because it depends entirely on what you plan to do with the system. The bare functional minimum is going to determine that and we have no idea of what that is for you or if it's going to change under certain circumstances.
  
  – Nasir Riley
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you understand the difference between shell variables and environment variables? If so, why is your question title "how to get the barest possible environment" when you're asking for shell variables that aren't environment variables to be removed?
  
  – Joseph Sible
  1 hour ago
  
  
  

  
  
  
  

add a comment | 

0

I am aware of

/usr/bin/env -i /bin/bash --login --norc --noprofile

And indeed, If I run the above, and immediately after run printenv in the new shell session, I see that very few exported variables are defined:

% /usr/bin/env -i /bin/bash --login --norc --noprofile

bash-4.4$ printenv | /usr/bin/perl -lpe 's/=.*//'

PWD

SHLVL

_

bash-4.4$ 

But if instead I run set, I see a lot of variables:

bash-4.4$ set | /usr/bin/perl -lpe 's/=.*//'

BASH

BASHOPTS

BASH_ALIASES

BASH_ARGC

BASH_ARGV

BASH_CMDS

BASH_LINENO

BASH_SOURCE

BASH_VERSINFO

BASH_VERSION

COLUMNS

DIRSTACK

EUID

GROUPS

HISTFILE

HISTFILESIZE

HISTSIZE

HOSTNAME

HOSTTYPE

IFS

LINES

MACHTYPE

MAILCHECK

OPTERR

OPTIND

OSTYPE

PATH

PPID

PS1

PS2

PS4

PWD

SHELL

SHELLOPTS

SHLVL

TERM

UID

_

bash-4.4$ 

For the sake of this question, let me define a shell variable as being "indispensable" iff bash simply won't run unless this variable is present (as indicated by its showing up in set's output). For example, PPID appears to be indispensable. (bash emits an error if one tries to unset it.)

What is the easiest way to reduce the set of defined variables to hold only the indispensable ones?

shell environment-variables

share|improve this question

edited 34 mins ago

kjo

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Your question is too broad and would be impossible for anyone to completely answer because it depends entirely on what you plan to do with the system. The bare functional minimum is going to determine that and we have no idea of what that is for you or if it's going to change under certain circumstances.
  
  – Nasir Riley
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you understand the difference between shell variables and environment variables? If so, why is your question title "how to get the barest possible environment" when you're asking for shell variables that aren't environment variables to be removed?
  
  – Joseph Sible
  1 hour ago
  
  
  

  
  
  
  

add a comment | 

I am aware of

/usr/bin/env -i /bin/bash --login --norc --noprofile

And indeed, If I run the above, and immediately after run printenv in the new shell session, I see that very few exported variables are defined:

% /usr/bin/env -i /bin/bash --login --norc --noprofile

bash-4.4$ printenv | /usr/bin/perl -lpe 's/=.*//'

PWD

SHLVL

_

bash-4.4$ 

But if instead I run set, I see a lot of variables:

bash-4.4$ set | /usr/bin/perl -lpe 's/=.*//'

BASH

BASHOPTS

BASH_ALIASES

BASH_ARGC

BASH_ARGV

BASH_CMDS

BASH_LINENO

BASH_SOURCE

BASH_VERSINFO

BASH_VERSION

COLUMNS

DIRSTACK

EUID

GROUPS

HISTFILE

HISTFILESIZE

HISTSIZE

HOSTNAME

HOSTTYPE

IFS

LINES

MACHTYPE

MAILCHECK

OPTERR

OPTIND

OSTYPE

PATH

PPID

PS1

PS2

PS4

PWD

SHELL

SHELLOPTS

SHLVL

TERM

UID

_

bash-4.4$ 

For the sake of this question, let me define a shell variable as being "indispensable" iff bash simply won't run unless this variable is present (as indicated by its showing up in set's output). For example, PPID appears to be indispensable. (bash emits an error if one tries to unset it.)

What is the easiest way to reduce the set of defined variables to hold only the indispensable ones?

shell environment-variables

share|improve this question

edited 34 mins ago

kjo

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

/usr/bin/env -i /bin/bash --login --norc --noprofile

% /usr/bin/env -i /bin/bash --login --norc --noprofile

bash-4.4$ printenv | /usr/bin/perl -lpe 's/=.*//'

PWD

SHLVL

_

bash-4.4$ 

bash-4.4$ set | /usr/bin/perl -lpe 's/=.*//'

BASH

BASHOPTS

BASH_ALIASES

BASH_ARGC

BASH_ARGV

BASH_CMDS

BASH_LINENO

BASH_SOURCE

BASH_VERSINFO

BASH_VERSION

COLUMNS

DIRSTACK

EUID

GROUPS

HISTFILE

HISTFILESIZE

HISTSIZE

HOSTNAME

HOSTTYPE

IFS

LINES

MACHTYPE

MAILCHECK

OPTERR

OPTIND

OSTYPE

PATH

PPID

PS1

PS2

PS4

PWD

SHELL

SHELLOPTS

SHLVL

TERM

UID

_

bash-4.4$ 

share|improve this question

edited 34 mins ago

kjo

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

share|improve this question

edited 34 mins ago

kjo

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges

asked 1 hour ago

kjokjo

4,5211313 gold badges4141 silver badges7373 bronze badges