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Old 09-29-2010, 10:44 PM   #1
ahtoot
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Registered: Jun 2005
Posts: 22

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Appending to PROMPT_COMMAND


I have the following as my $PROMPT_COMMAND in .bashrc:

Code:
PROMPT_COMMAND='
if [ $TERM = "screen" ]; then
 MYPWD="${PWD/#$HOME/~}"
 [ ${#MYPWD} -gt 20 ] && MYPWD=..${MYPWD:${#MYPWD}-18}
 echo -n -e "\033k$MYPWD\033\\"
fi
'
I am trying to append items to my PROMPT_COMMAND in another script/on command line. If I do the following:

Code:
export PROMPT_COMMAND="$PROMPT_COMMAND && ls"
bash has a syntax error and complains of unexpected token near &&.
But if I change the following in .bashrc

Code:
PROMPT_COMMAND='
if [ $TERM = "screen" ]; then
 MYPWD="${PWD/#$HOME/~}"
 [ ${#MYPWD} -gt 20 ] && MYPWD=..${MYPWD:${#MYPWD}-18}
 echo -n -e "\033k$MYPWD\033\\"
fi && ls
'
I get no error.

I've echoed the value of $PROMPT_COMMAND in both cases and their output is exactly the same.


Any tips? Thanks.
 
Old 09-29-2010, 11:08 PM   #2
Meson
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It probably has to do with the fact that you already have quotes inside the original prompt command.
 
Old 09-29-2010, 11:33 PM   #3
grail
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Registered: Sep 2009
Location: Perth
Distribution: Manjaro
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I am curious what you expect to happen?

If you did the following on the command line:
Code:
PROMPT_COMMAND="$PROMPT_COMMAND && ls"
And now perform an echo, all that has happened is '&& ls' gets appended to the string.

The questions then becomes, what is processing $PROMPT_COMMAND?
 
Old 09-30-2010, 01:08 AM   #4
ahtoot
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Registered: Jun 2005
Posts: 22

Original Poster
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Quote:
Originally Posted by grail View Post
I am curious what you expect to happen?

If you did the following on the command line:
Code:
PROMPT_COMMAND="$PROMPT_COMMAND && ls"
And now perform an echo, all that has happened is '&& ls' gets appended to the string.

The questions then becomes, what is processing $PROMPT_COMMAND?
bash is processing $PROMPT_COMMAND
http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x264.html


I've solved it, I had to put the last quote on the same line as the last fi

Code:
PROMPT_COMMAND='
if [ $TERM = "screen" ]; then
 MYPWD="${PWD/#$HOME/~}"
 [ ${#MYPWD} -gt 20 ] && MYPWD=..${MYPWD:${#MYPWD}-18}
 echo -n -e "\033k$MYPWD\033\\"
fi'

Now if someone can tell me why the previous version didn't work..

Code:
PROMPT_COMMAND='
if [ $TERM = "screen" ]; then
 MYPWD="${PWD/#$HOME/~}"
 [ ${#MYPWD} -gt 20 ] && MYPWD=..${MYPWD:${#MYPWD}-18}
 echo -n -e "\033k$MYPWD\033\\"
fi
'
Edit: Maybe because && can't start on a newline?

Last edited by ahtoot; 09-30-2010 at 01:10 AM.
 
Old 09-30-2010, 01:12 AM   #5
catkin
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Registered: Dec 2008
Location: Tamil Nadu, India
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Because the fi command needs to be terminated -- by a ; or by a newline.
 
  


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