Installing “app-portage/eix” in Gentoo to manage your portage updates you might encounter this error, when trying to use “eix” for the first time:

Writing database file /var/cache/eix/portage.eix...
cannot open database file /var/cache/eix/portage.eix for writing (mode = 'wb')

The chances are missing directory “/var/cache/eix/” or the user:group of the “/var/cache/eix/” is root:root, which is NOT right.

The user:group must be “portage:portage”.

So the solution is really simple:

mkdir -p /var/cache/eix
chown portage:portage /var/cache/eix

Output – the errors you might get

Using the eix-sync failed with:

root@srv1 ~ # eix-sync 
 * eix-cache does not exist
 * Running eix-update
Reading Portage settings...
Building database (/var/cache/eix/portage.eix)...
[0] "gentoo" /usr/portage/ (cache: metadata-md5-or-flat)
     Reading category 167|167 (100) Finished             
[1] "myportage" /usr/local/myportage (cache: parse|ebuild*#metadata-md5#metadata-flat#assign)
     Reading category 167|167 (100) Finished    
Applying masks...
Calculating hash tables...
Writing database file /var/cache/eix/portage.eix...
cannot open database file /var/cache/eix/portage.eix for writing (mode = 'wb')
 * eix-update failed
 * Time statistics:
     6 seconds for initial eix-update
     6 seconds total

Using the “eix-update” failed, too.

root@srv ~ # eix-update 
Reading Portage settings...
Building database (/var/cache/eix/portage.eix)...
[0] "gentoo" /usr/portage/ (cache: metadata-md5-or-flat)
     Reading category 167|167 (100) Finished             
[1] "myportage" /usr/local/myportage (cache: parse|ebuild*#metadata-md5#metadata-flat#assign)
     Reading category 167|167 (100) Finished    
Applying masks...
Calculating hash tables...
Writing database file /var/cache/eix/portage.eix...
cannot open database file /var/cache/eix/portage.eix for writing (mode = 'wb')

Output 2 – Successful update with eix

root@srv ~ # eix-update 
Reading Portage settings...
Building database (/var/cache/eix/portage.eix)...
[0] "gentoo" /usr/portage/ (cache: metadata-md5-or-flat)
     Reading category 167|167 (100) Finished             
[1] "myportage" /usr/local/myportage (cache: parse|ebuild*#metadata-md5#metadata-flat#assign)
     Reading category 167|167 (100) Finished    
Applying masks...
Calculating hash tables...
Writing database file /var/cache/eix/portage.eix...
Database contains 19544 packages in 167 categories