How to trick a program into thinking there is no X server running

Clash Royale CLAN TAG#URR8PPP

up vote
12
down vote

favorite

1

I have this program that can run with both a text user interface and a graphical user interface.

It lacks any command line switch to force one or the other, rather I guess it somehow auto-detects whether we are in X or not (e.g. if I run it from a virtual terminal it enters its text mode, and if I run it from an X terminal emulator it opens a separate graphical window).

I'd like to force it into text mode and have it run inside the X terminal. How would I go about doing it?

x11

share|improve this question

edited 16 mins ago

progo

874712

asked 16 hours ago

Luka Aleksić

635

add a comment | 

up vote
12
down vote

favorite

1

I have this program that can run with both a text user interface and a graphical user interface.

It lacks any command line switch to force one or the other, rather I guess it somehow auto-detects whether we are in X or not (e.g. if I run it from a virtual terminal it enters its text mode, and if I run it from an X terminal emulator it opens a separate graphical window).

I'd like to force it into text mode and have it run inside the X terminal. How would I go about doing it?

x11

share|improve this question

edited 16 mins ago

progo

874712

asked 16 hours ago

Luka Aleksić

635

add a comment | 

up vote
12
down vote

favorite

1

up vote
12
down vote

favorite

1

1

I have this program that can run with both a text user interface and a graphical user interface.

It lacks any command line switch to force one or the other, rather I guess it somehow auto-detects whether we are in X or not (e.g. if I run it from a virtual terminal it enters its text mode, and if I run it from an X terminal emulator it opens a separate graphical window).

I'd like to force it into text mode and have it run inside the X terminal. How would I go about doing it?

x11

share|improve this question

edited 16 mins ago

progo

874712

asked 16 hours ago

Luka Aleksić

635

I have this program that can run with both a text user interface and a graphical user interface.

It lacks any command line switch to force one or the other, rather I guess it somehow auto-detects whether we are in X or not (e.g. if I run it from a virtual terminal it enters its text mode, and if I run it from an X terminal emulator it opens a separate graphical window).

I'd like to force it into text mode and have it run inside the X terminal. How would I go about doing it?

x11

x11

share|improve this question

edited 16 mins ago

progo

874712

asked 16 hours ago

Luka Aleksić

635

share|improve this question

edited 16 mins ago

progo

874712

asked 16 hours ago

Luka Aleksić

635

share|improve this question

share|improve this question

edited 16 mins ago

progo

874712

edited 16 mins ago

progo

874712

edited 16 mins ago

progo

874712

874712

asked 16 hours ago

Luka Aleksić

635

asked 16 hours ago

Luka Aleksić

635

asked 16 hours ago

Luka Aleksić

635

635

add a comment | 

add a comment | 

2 Answers
2

active

oldest

votes

up vote
21
down vote



accepted

Usually just

unset DISPLAY

in command-line of the terminal. Some applications are smarter than that, and actually check permissions and type of the console versus pseudoterminal.

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. It worked.
  – Luka Aleksić
  15 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
  – Kevin
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  @Kevin maybe DISPLAY=invalid:0 ?
  – sourcejedi
  13 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
  – Thomas Dickey
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
  – sourcejedi
  10 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

up vote
8
down vote

If you want to disable X for a single command you can write

DISPLAY= ./my_command

Notice the strategical blank space after =. More generally, you can set environment variables for a process by prefixing your command with a sequence of <variable>=<value> separated by spaces. Since space serves as separator, = immediately followed by a space clears the preceding variable. For instance:

A=a B=b C= D=d sh -c 'echo $A $B $C $D'

This will print

a b d

(I'm using sh -c and single-quotes to prevent from substitution happening in the current shell, in other words, this ensures that we actually print the environment variables that the subprocess sees. Note that shell substitution happens before the individual arguments are passed to the subprocess, so there's only a single space between b and d in the output, just as if the command line were echo a b d [with two spaces].)

share|improve this answer

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

tobi_s 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 | 

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
21
down vote



accepted

Usually just

unset DISPLAY

in command-line of the terminal. Some applications are smarter than that, and actually check permissions and type of the console versus pseudoterminal.

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. It worked.
  – Luka Aleksić
  15 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
  – Kevin
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  @Kevin maybe DISPLAY=invalid:0 ?
  – sourcejedi
  13 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
  – Thomas Dickey
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
  – sourcejedi
  10 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

up vote
21
down vote



accepted

Usually just

unset DISPLAY

in command-line of the terminal. Some applications are smarter than that, and actually check permissions and type of the console versus pseudoterminal.

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. It worked.
  – Luka Aleksić
  15 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
  – Kevin
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  @Kevin maybe DISPLAY=invalid:0 ?
  – sourcejedi
  13 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
  – Thomas Dickey
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
  – sourcejedi
  10 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

up vote
21
down vote



accepted

up vote
21
down vote



accepted

Usually just

unset DISPLAY

in command-line of the terminal. Some applications are smarter than that, and actually check permissions and type of the console versus pseudoterminal.

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

Usually just

unset DISPLAY

in command-line of the terminal. Some applications are smarter than that, and actually check permissions and type of the console versus pseudoterminal.

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

share|improve this answer

share|improve this answer

answered 15 hours ago

Thomas Dickey

50.8k589161

answered 15 hours ago

Thomas Dickey

50.8k589161

answered 15 hours ago

Thomas Dickey

50.8k589161

50.8k589161

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. It worked.
  – Luka Aleksić
  15 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
  – Kevin
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  @Kevin maybe DISPLAY=invalid:0 ?
  – sourcejedi
  13 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
  – Thomas Dickey
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
  – sourcejedi
  10 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. It worked.
  – Luka Aleksić
  15 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
  – Kevin
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  @Kevin maybe DISPLAY=invalid:0 ?
  – sourcejedi
  13 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
  – Thomas Dickey
  13 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
  – sourcejedi
  10 hours ago
  
  

  
  
  
  

Thanks. It worked.
– Luka Aleksić
15 hours ago

Thanks. It worked.
– Luka Aleksić
15 hours ago

2

2

Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
– Kevin
14 hours ago

Unfortunately, some really obstinate software will assume DISPLAY=:0 if it's unset. I believe you can fix that by running it under a different user and using iptables to drop loopback X11, but that's pretty gross.
– Kevin
14 hours ago

1

1

@Kevin maybe DISPLAY=invalid:0 ?
– sourcejedi
13 hours ago

@Kevin maybe DISPLAY=invalid:0 ?
– sourcejedi
13 hours ago

no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
– Thomas Dickey
13 hours ago

no... that would only try to make the program connect to the display on "invalid". It might not timeout rapidly enough to be useful.
– Thomas Dickey
13 hours ago

@ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
– sourcejedi
10 hours ago

@ThomasDickey fite me :-). There are two X libraries, and the old one was migrated to be a wrapper for the new low-level one. At least on my machine, xterm knows to fail near-instantly on NXDOMAIN.
– sourcejedi
10 hours ago

 | 
show 1 more comment

up vote
8
down vote

If you want to disable X for a single command you can write

DISPLAY= ./my_command

Notice the strategical blank space after =. More generally, you can set environment variables for a process by prefixing your command with a sequence of <variable>=<value> separated by spaces. Since space serves as separator, = immediately followed by a space clears the preceding variable. For instance:

A=a B=b C= D=d sh -c 'echo $A $B $C $D'

This will print

a b d

(I'm using sh -c and single-quotes to prevent from substitution happening in the current shell, in other words, this ensures that we actually print the environment variables that the subprocess sees. Note that shell substitution happens before the individual arguments are passed to the subprocess, so there's only a single space between b and d in the output, just as if the command line were echo a b d [with two spaces].)

share|improve this answer

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

tobi_s 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 | 

up vote
8
down vote

If you want to disable X for a single command you can write

DISPLAY= ./my_command

Notice the strategical blank space after =. More generally, you can set environment variables for a process by prefixing your command with a sequence of <variable>=<value> separated by spaces. Since space serves as separator, = immediately followed by a space clears the preceding variable. For instance:

A=a B=b C= D=d sh -c 'echo $A $B $C $D'

This will print

a b d

(I'm using sh -c and single-quotes to prevent from substitution happening in the current shell, in other words, this ensures that we actually print the environment variables that the subprocess sees. Note that shell substitution happens before the individual arguments are passed to the subprocess, so there's only a single space between b and d in the output, just as if the command line were echo a b d [with two spaces].)

share|improve this answer

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

tobi_s 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 | 

up vote
8
down vote

up vote
8
down vote

If you want to disable X for a single command you can write

DISPLAY= ./my_command

Notice the strategical blank space after =. More generally, you can set environment variables for a process by prefixing your command with a sequence of <variable>=<value> separated by spaces. Since space serves as separator, = immediately followed by a space clears the preceding variable. For instance:

A=a B=b C= D=d sh -c 'echo $A $B $C $D'

This will print

a b d

(I'm using sh -c and single-quotes to prevent from substitution happening in the current shell, in other words, this ensures that we actually print the environment variables that the subprocess sees. Note that shell substitution happens before the individual arguments are passed to the subprocess, so there's only a single space between b and d in the output, just as if the command line were echo a b d [with two spaces].)

share|improve this answer

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

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

If you want to disable X for a single command you can write

DISPLAY= ./my_command

Notice the strategical blank space after =. More generally, you can set environment variables for a process by prefixing your command with a sequence of <variable>=<value> separated by spaces. Since space serves as separator, = immediately followed by a space clears the preceding variable. For instance:

A=a B=b C= D=d sh -c 'echo $A $B $C $D'

This will print

a b d

(I'm using sh -c and single-quotes to prevent from substitution happening in the current shell, in other words, this ensures that we actually print the environment variables that the subprocess sees. Note that shell substitution happens before the individual arguments are passed to the subprocess, so there's only a single space between b and d in the output, just as if the command line were echo a b d [with two spaces].)

share|improve this answer

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

tobi_s 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 answer

share|improve this answer

edited 6 hours ago

edited 6 hours ago

edited 6 hours ago

answered 8 hours ago

tobi_s

1812

New contributor

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

answered 8 hours ago

tobi_s

1812

answered 8 hours ago

tobi_s

1812

1812

New contributor

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

New contributor

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

tobi_s 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 | 

add a comment | 

 

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