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1

This:

echo $VAR

yields: something

And this:

[[ -z "$VAR" ]]
echo $?

yields: 1

Yet this:

if [[ -z "$TMUX_MAN_PANE" ]]; then
echo 'NEVER PRINTS!'


This screws with my head and I need some kind logical way to think about this before I go insane.

UPDATE

Here's some real code. I can't get this to fucking work for the life of me. Fuck bash. :)

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  tmux list-panes -t $TMUX_MAN_PANE &> /dev/null

  echo $?

  echo $TMUX_MAN_PANE

  [[ -z "$TMUX_MAN_PANE" ]]

  echo $?

  if ! [[ -z "$TMUX_MAN_PANE" ]] && [[ $? ]]; then

    echo luck

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    echo fuck

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}

UPDATE 2: Success

Finally figured it out. Was hvaing a hell of a time getting the status of the first line in the if statement. Had to do some trickery to get the output of the tmux statement in the first line of the if statement. If anyone knows a cleaner way to do this, I'm all ears.

Holy shit, I don't know how people program in Bash. Drives me nuts. Sorry for the foul language. I was apeshit. :) Here's the working code:

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  fucker=$(tmux list-panes -t $TMUX_MAN_PANE 2>&1)

  if ! [[ -z "$TMUX_MAN_PANE" ]] && ! [[ $fucker =~ 'find pane' ]]; then

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}



tmux_man_page_close() {

  if [ $TMUX_MAN_PANE ]; then

     tmux kill-pane -t $TMUX_MAN_PANE

  fi

}

bash

share|improve this question

edited 37 mins ago

StevieD

asked 1 hour ago

StevieDStevieD

1679

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Your update does not include enough information. Please (a) include the values of TERM, TMUX, and TMUX_MAN_PANE from before the function runs and (b) include the output of the function and then (c) explain how that output differs from what you expect.
  
  – John1024
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It's all a mess. In the first line of the if statement, I just want to know if that command is throwing an error. There is no seemingly rational way to do that. I don't want the output from the command, I want to know if it's throwing an error. That's it.
  
  – StevieD
  58 mins ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It's showing the command was a success even though it can't find the pane. I see no way to extract the output from that tmux command.
  
  – StevieD
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I should just be going this in perl. Fuck this crazy shit.
  
  – StevieD
  46 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Jesus, finally figured it out. Posting solution.
  
  – StevieD
  41 mins ago
  
  
  

  
  
  
  

add a comment | 

1

This:

echo $VAR

yields: something

And this:

[[ -z "$VAR" ]]
echo $?

yields: 1

Yet this:

if [[ -z "$TMUX_MAN_PANE" ]]; then
echo 'NEVER PRINTS!'


This screws with my head and I need some kind logical way to think about this before I go insane.

UPDATE

Here's some real code. I can't get this to fucking work for the life of me. Fuck bash. :)

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  tmux list-panes -t $TMUX_MAN_PANE &> /dev/null

  echo $?

  echo $TMUX_MAN_PANE

  [[ -z "$TMUX_MAN_PANE" ]]

  echo $?

  if ! [[ -z "$TMUX_MAN_PANE" ]] && [[ $? ]]; then

    echo luck

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    echo fuck

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}

UPDATE 2: Success

Finally figured it out. Was hvaing a hell of a time getting the status of the first line in the if statement. Had to do some trickery to get the output of the tmux statement in the first line of the if statement. If anyone knows a cleaner way to do this, I'm all ears.

Holy shit, I don't know how people program in Bash. Drives me nuts. Sorry for the foul language. I was apeshit. :) Here's the working code:

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  fucker=$(tmux list-panes -t $TMUX_MAN_PANE 2>&1)

  if ! [[ -z "$TMUX_MAN_PANE" ]] && ! [[ $fucker =~ 'find pane' ]]; then

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}



tmux_man_page_close() {

  if [ $TMUX_MAN_PANE ]; then

     tmux kill-pane -t $TMUX_MAN_PANE

  fi

}

bash

share|improve this question

edited 37 mins ago

StevieD

asked 1 hour ago

StevieDStevieD

1679

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Your update does not include enough information. Please (a) include the values of TERM, TMUX, and TMUX_MAN_PANE from before the function runs and (b) include the output of the function and then (c) explain how that output differs from what you expect.
  
  – John1024
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It's all a mess. In the first line of the if statement, I just want to know if that command is throwing an error. There is no seemingly rational way to do that. I don't want the output from the command, I want to know if it's throwing an error. That's it.
  
  – StevieD
  58 mins ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It's showing the command was a success even though it can't find the pane. I see no way to extract the output from that tmux command.
  
  – StevieD
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I should just be going this in perl. Fuck this crazy shit.
  
  – StevieD
  46 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Jesus, finally figured it out. Posting solution.
  
  – StevieD
  41 mins ago
  
  
  

  
  
  
  

add a comment | 

This:

echo $VAR

yields: something

And this:

[[ -z "$VAR" ]]
echo $?

yields: 1

Yet this:

if [[ -z "$TMUX_MAN_PANE" ]]; then
echo 'NEVER PRINTS!'


This screws with my head and I need some kind logical way to think about this before I go insane.

UPDATE

Here's some real code. I can't get this to fucking work for the life of me. Fuck bash. :)

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  tmux list-panes -t $TMUX_MAN_PANE &> /dev/null

  echo $?

  echo $TMUX_MAN_PANE

  [[ -z "$TMUX_MAN_PANE" ]]

  echo $?

  if ! [[ -z "$TMUX_MAN_PANE" ]] && [[ $? ]]; then

    echo luck

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    echo fuck

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}

UPDATE 2: Success

Finally figured it out. Was hvaing a hell of a time getting the status of the first line in the if statement. Had to do some trickery to get the output of the tmux statement in the first line of the if statement. If anyone knows a cleaner way to do this, I'm all ears.

Holy shit, I don't know how people program in Bash. Drives me nuts. Sorry for the foul language. I was apeshit. :) Here's the working code:

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  fucker=$(tmux list-panes -t $TMUX_MAN_PANE 2>&1)

  if ! [[ -z "$TMUX_MAN_PANE" ]] && ! [[ $fucker =~ 'find pane' ]]; then

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}



tmux_man_page_close() {

  if [ $TMUX_MAN_PANE ]; then

     tmux kill-pane -t $TMUX_MAN_PANE

  fi

}

bash

share|improve this question

edited 37 mins ago

StevieD

asked 1 hour ago

StevieDStevieD

1679

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  tmux list-panes -t $TMUX_MAN_PANE &> /dev/null

  echo $?

  echo $TMUX_MAN_PANE

  [[ -z "$TMUX_MAN_PANE" ]]

  echo $?

  if ! [[ -z "$TMUX_MAN_PANE" ]] && [[ $? ]]; then

    echo luck

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    echo fuck

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}

tmux_man_page() {

if [[ "$TERM" =~ 'screen' ]] && [[ -n "$TMUX" ]]; then

  fucker=$(tmux list-panes -t $TMUX_MAN_PANE 2>&1)

  if ! [[ -z "$TMUX_MAN_PANE" ]] && ! [[ $fucker =~ 'find pane' ]]; then

    tmux -q respawn-pane -k -t $TMUX_MAN_PANE man $1

  else

    tmux split-window -vf man $1

    TMUX_MAN_PANE=$(tmux display-message -p "#{pane_id}")

    export TMUX_MAN_PANE

    tmux select-pane -t {last}

  fi

fi

}



tmux_man_page_close() {

  if [ $TMUX_MAN_PANE ]; then

     tmux kill-pane -t $TMUX_MAN_PANE

  fi

}

share|improve this question

edited 37 mins ago

StevieD

asked 1 hour ago

StevieDStevieD

1679

share|improve this question

edited 37 mins ago

StevieD

asked 1 hour ago

StevieDStevieD

1679

asked 1 hour ago

StevieDStevieD

1679

asked 1 hour ago

StevieDStevieD

1679

1 Answer
1

active

oldest

votes

4

The key is that 0 means true and 1 (or any other non-zero value) means false.

In shell, a test that is true (or a program which completes successfully), exits with code 0. The test [[ -z "$VAR" ]] returns code zero (true) if $VAR is empty or one (false) if it is not empty:

$ var=""; [[ -z "$var" ]]; echo $?

0

$ var="NOT EMPTY"; [[ -z "$var" ]]; echo $?

1

In sum, if $VAR is non-empty, then [[ -z "$VAR" ]] is false (returns 1) and the then statement does not execute.

Did you intend for the test to return true if the variable was non-empty? If so, replace -z with -n:

$ var=""; [[ -n "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ -n "$var" ]]; echo $?

0

For brevity, the same test is performed if -n is omitted:

$ var=""; [[ "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ "$var" ]]; echo $?

0

share|improve this answer

edited 1 hour ago

answered 1 hour ago

John1024John1024

48.4k5113128

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I just posted my real code. I cannot, for the life of me, get that to work. I'm literally going fucking nuts.
  
  – StevieD
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @StevieD Run set -x and then run your code. This will show you how every step is evaluated.
  
  – John1024
  1 hour ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Ah, shit. Forgot about that setting. I'll try it.
  
  – StevieD
  1 hour ago
  

  
  
  
  

add a comment | 

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4

The key is that 0 means true and 1 (or any other non-zero value) means false.

In shell, a test that is true (or a program which completes successfully), exits with code 0. The test [[ -z "$VAR" ]] returns code zero (true) if $VAR is empty or one (false) if it is not empty:

$ var=""; [[ -z "$var" ]]; echo $?

0

$ var="NOT EMPTY"; [[ -z "$var" ]]; echo $?

1

In sum, if $VAR is non-empty, then [[ -z "$VAR" ]] is false (returns 1) and the then statement does not execute.

Did you intend for the test to return true if the variable was non-empty? If so, replace -z with -n:

$ var=""; [[ -n "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ -n "$var" ]]; echo $?

0

For brevity, the same test is performed if -n is omitted:

$ var=""; [[ "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ "$var" ]]; echo $?

0

share|improve this answer

edited 1 hour ago

answered 1 hour ago

John1024John1024

48.4k5113128

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I just posted my real code. I cannot, for the life of me, get that to work. I'm literally going fucking nuts.
  
  – StevieD
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @StevieD Run set -x and then run your code. This will show you how every step is evaluated.
  
  – John1024
  1 hour ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Ah, shit. Forgot about that setting. I'll try it.
  
  – StevieD
  1 hour ago
  

  
  
  
  

add a comment | 

4

The key is that 0 means true and 1 (or any other non-zero value) means false.

In shell, a test that is true (or a program which completes successfully), exits with code 0. The test [[ -z "$VAR" ]] returns code zero (true) if $VAR is empty or one (false) if it is not empty:

$ var=""; [[ -z "$var" ]]; echo $?

0

$ var="NOT EMPTY"; [[ -z "$var" ]]; echo $?

1

In sum, if $VAR is non-empty, then [[ -z "$VAR" ]] is false (returns 1) and the then statement does not execute.

Did you intend for the test to return true if the variable was non-empty? If so, replace -z with -n:

$ var=""; [[ -n "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ -n "$var" ]]; echo $?

0

For brevity, the same test is performed if -n is omitted:

$ var=""; [[ "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ "$var" ]]; echo $?

0

share|improve this answer

edited 1 hour ago

answered 1 hour ago

John1024John1024

48.4k5113128

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I just posted my real code. I cannot, for the life of me, get that to work. I'm literally going fucking nuts.
  
  – StevieD
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @StevieD Run set -x and then run your code. This will show you how every step is evaluated.
  
  – John1024
  1 hour ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Ah, shit. Forgot about that setting. I'll try it.
  
  – StevieD
  1 hour ago
  

  
  
  
  

add a comment | 

The key is that 0 means true and 1 (or any other non-zero value) means false.

In shell, a test that is true (or a program which completes successfully), exits with code 0. The test [[ -z "$VAR" ]] returns code zero (true) if $VAR is empty or one (false) if it is not empty:

$ var=""; [[ -z "$var" ]]; echo $?

0

$ var="NOT EMPTY"; [[ -z "$var" ]]; echo $?

1

In sum, if $VAR is non-empty, then [[ -z "$VAR" ]] is false (returns 1) and the then statement does not execute.

Did you intend for the test to return true if the variable was non-empty? If so, replace -z with -n:

$ var=""; [[ -n "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ -n "$var" ]]; echo $?

0

For brevity, the same test is performed if -n is omitted:

$ var=""; [[ "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ "$var" ]]; echo $?

0

share|improve this answer

edited 1 hour ago

answered 1 hour ago

John1024John1024

48.4k5113128

$ var=""; [[ -z "$var" ]]; echo $?

0

$ var="NOT EMPTY"; [[ -z "$var" ]]; echo $?

1

$ var=""; [[ -n "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ -n "$var" ]]; echo $?

0

$ var=""; [[ "$var" ]]; echo $?

1

$ var="NOT EMPTY"; [[ "$var" ]]; echo $?

0

share|improve this answer

edited 1 hour ago

answered 1 hour ago

John1024John1024

48.4k5113128

answered 1 hour ago

John1024John1024

48.4k5113128

answered 1 hour ago

John1024John1024

48.4k5113128