How to Pre-Invoke {"mount -o remount,rw /usr";}; with /etc/apt/apt.conf?

[Shaul Karl <shaulk@israsrv.net.il>]

I tried to change the Pre-Invoke and Post-Invoke lines of /etc/apt/apt.conf so 
that it would pre mount and post mount my /usr which is normally mounted ro, 
but failed.
How should I do it correctly?

[02:55:56 /tmp]$ cat /etc/apt/apt.conf

// Options for APT in general
APT 
{
  Architecture "i386";
  
  // Options for apt-get
  Get 
  {
     Download-Only "false";
     Simulate "false";
     Assume-Yes "false";
     Force-Yes "false";             // I would never set this.
     Fix-Broken "false";  
     Fix-Missing "false";     
     Show-Upgraded "false";
     No-Upgrade "false";
     Print-URIs "false";
     Compile "false";
     No-Download "false";
     Purge "false";
     List-Cleanup "true";
  };

  Cache 
  {
     Important "false";
  };

  // Some general options
  Ignore-Hold "false";
  Immediate-Configure "true";      // DO NOT turn this off, see the man page
  Force-LoopBreak "false";         // DO NOT turn this on, see the man page
};

// Options for the downloading routines
Acquire
{
  Queue-Mode "host";       // host|access
  Retries "0";
  Source-Symlinks "true";
  
  // HTTP method configuration
  http 
  {
    Proxy "http://Proxy.israsrv.net.il:8080";;

    Timeout "120";
    
    // Cache Control. Note these do not work with Squid 2.0.2
    No-Cache "false";
    Max-Age "86400";     // 1 Day age on index files
    No-Store "false";    // Prevent the cache from storing archives    
  };

  // FTP method configuration
  ftp
  {
    Proxy "ftp://Proxy.israsrv.net.il:8080";;

    Timeout "120";
									       
    ProxyLogin
    {
       "USER anonymous@ftp.tau.ac.il:21";
       "PASS shaulk@israsrv.net.il";
    };
					
    /* Passive mode control, proxy, non-proxy and per-host. Pasv mode
       is prefered if possible */
    Passive "true";
  };

// Directory layout
Dir 
{
  // Location of the state dir
  State "/var/state/apt/" 
  {
     lists "lists/";
     xstatus "xstatus";
     userstatus "status.user";
     status "/var/lib/dpkg/status";
     cdroms "cdroms.list";
  };
  
  // Location of the cache dir
  Cache "/var/cache/apt/" {
     archives "archives/";
     srcpkgcache "srcpkgcache.bin";
     pkgcache "pkgcache.bin";     
  };
  
  // Config files
  Etc "/etc/apt/" {
     sourcelist "sources.list";
     main "apt.conf";
  };
  
  // Locations of binaries
  Bin {
     methods "/usr/lib/apt/methods/";
     gzip "/bin/gzip";
     dpkg "/usr/bin/dpkg";
     dpkg-source "/usr/bin/dpkg-source";
     dpkg-buildpackage "/usr/bin/dpkg-buildpackage"
     apt-get "/usr/bin/apt-get";
     apt-cache "/usr/bin/apt-cache";
  };
};

// Things that effect the APT dselect method
DSelect 
{
   Clean "auto";   // always|auto|prompt|never
   Options "-f";
   UpdateOptions "";
   PromptAfterUpdate "no";
}

DPkg 
{
   // Probably don't want to set this one.
   Options {"--force-downgrade";}
   
   // Auto re-mounting of a readonly /usr
   Pre-Invoke {"mount -o remount,rw /usr";};
   Post-Invoke {"mount -o remount,ro /usr";};
   
   // Prevents daemons from getting cwd as something mountable (default)
   Run-Directory "/";
   
   // Build options for apt-get source --compile
   Build-Options "-b -uc";

}

/* Options you can set to see some debugging text They corrispond to names
   of classes in the source code */
Debug 
{
  pkgProblemResolver "false";
  pkgAcquire "false";
  pkgAcquire::Worker "false";
  pkgDPkgPM "false";
  
  pkgInitialize "false";   // This one will dump the configuration space
  NoLocking "false";
  Acquire::Ftp "false";    // Show ftp command traffic
  aptcdrom "false";        // Show found package files
}
// Pre-configure all packages before they are installed.
DPkg::Pre-Install-Pkgs {"dpkg-preconfig --apt";};
[02:56:49 /tmp]$