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I don't have g++:

erelsgl@ubuntu:/etc/apt$ which g++
erelsgl@ubuntu:/etc/apt$ 

erelsgl@ubuntu:/etc/apt$ g++
The program 'g++' can be found in the following packages:
 * g++
 * pentium-builder
Try: sudo apt-get install <selected package>

So I try to install it:

erelsgl@ubuntu:~/srilm$ sudo apt-get install g++
Reading package lists... Done
Building dependency tree       
Reading state information... Done
g++ is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 5 not upgraded.
2 not fully installed or removed.
After this operation, 0B of additional disk space will be used.
Setting up g++ (4:4.4.3-1ubuntu1) ...
update-alternatives: error: alternative path /usr/bin/g++ doesn't exist.
dpkg: error processing g++ (--configure):
 subprocess installed post-installation script returned error exit status 2
dpkg: dependency problems prevent configuration of build-essential:
 build-essential depends on g++ (>= 4:4.3.1); however:
  Package g++ is not configured yet.
dpkg: error processing build-essential (--configure):
 dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
                                                                                                          Errors were encountered while processing:
 g++
 build-essential
E: Sub-process /usr/bin/dpkg returned an error code (1)

I also try to install build-essential, and get same results.

I also tried "sudo apt-get update" - didn't help.

This is my apt-cache:

erelsgl@ubuntu:/etc/apt$ apt-cache policy g++ build-essential
g++:
  Installed: 4:4.4.3-1ubuntu1
  Candidate: 4:4.4.3-1ubuntu1
  Version table:
 *** 4:4.4.3-1ubuntu1 0
        500 http://il.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status
build-essential:
  Installed: 11.4build1
  Candidate: 11.4build1
  Version table:
 *** 11.4build1 0
        500 http://il.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status
erelsgl@ubuntu:/etc/apt$ 

I also tried this and got the same error:

erelsgl@ubuntu:~/Ace/Files/corpus$ sudo dpkg --configure -a
Setting up g++ (4:4.4.3-1ubuntu1) ...
update-alternatives: error: alternative path /usr/bin/g++ doesn't exist.
dpkg: error processing g++ (--configure):
 subprocess installed post-installation script returned error exit status 2
dpkg: dependency problems prevent configuration of build-essential:
 build-essential depends on g++ (>= 4:4.3.1); however:
  Package g++ is not configured yet.
dpkg: error processing build-essential (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 g++
 build-essential
share|improve this question
    
Looks like you're running Ubuntu Lucid. Could you add the output of apt-cache policy g++ build-essential? – Lekensteyn Dec 15 '11 at 10:08
    
You are right! I added the output. – Erel Segal-Halevi Dec 15 '11 at 10:16

Sounds like there is a problem with your current g++ installation. First remove it:

Get your installed g++ package: dpkg --list 'g++'

Remove it: dpkg --purge g++XXXX

Then install it again: apt-get install g++

Going to the package with synaptic (gui) or aptitude (command-line) might also give more information about the status of the package.

share|improve this answer
    
This sounds promising, however I cannot figure out the output: erelsgl@ubuntu:~/Ace/Files/corpus$ sudo dpkg --list 'g++' Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Description +++-==============-==============-============================================ iF g++ 4:4.4.3-1ubunt The GNU C++ compiler – Erel Segal-Halevi Dec 18 '11 at 8:01
    
It seems I have version 4.4.3, but I cannot remove it: erelsgl@ubuntu:~/Ace/Files/corpus$ sudo dpkg --purge 'g++4.4.3' dpkg: warning: ignoring request to remove g++4.4.3 which isn't installed. I also tried 'g++-4.4.3', 'g++4.4.3-1ubunt', 'g++4.4.3-1ubuntu' 'g++-4.4.3-1ubunt', 'g++-4.4.3-1ubuntu' - I probably miss the correct variant – Erel Segal-Halevi Dec 18 '11 at 8:02
    
try just "dpkg --purge g++" – dtech Dec 22 '11 at 11:04
    
OK, the purge worked, but the install still gives the same error... – Erel Segal-Halevi Jan 1 '12 at 11:10

It sounds like g++ is half-installed. Try:

sudo dpkg --configure -a
share|improve this answer
    
I tried this and got the same error - see my latest edit above. – Erel Segal-Halevi Dec 18 '11 at 7:59
up vote 0 down vote accepted

I didn't find a solution to this and other similar problems in my Ubuntu 10.04, so finally I upgraded to 12.04 and now everything works fine... Sometimes, the package system gets confused, so the best solution is just to upgrade.

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