Você pode selecionar o perfil a ser usado na linha de comando com a opção --profile-directory :
chromium-browser --profile-directory="Profile 1"
chromium-browser --profile-directory="Default"
Para saber a lista de perfis disponíveis, veja ~/.config/chromium :
$ ls ~/.config/chromium
./ Profile 1/
../ Safe Browsing Bloom
Certificate Revocation Lists Safe Browsing Bloom Prefix Set
Channels Safe Browsing Cookies
chrome_shutdown_ms.txt Safe Browsing Cookies-journal
Crash Reports/ Safe Browsing Csd Whitelist
Default/ Safe Browsing Download
First Run Safe Browsing Download Whitelist
Local State Safe Browsing Extension Blacklist
pnacl/ Safe Browsing IP Blacklist
Fonte: link