Experience and skills for many Linux jobs include:
5+ years Linux System administration
Engineering experience DNS fundamentals and BIND Network fundamentals
Understanding of Firewalls, Load balancers and database servers.
Working knowledge of Apache web server, PHP and MySQL VMWare
Experience and working knowledge with JBoss, NIS, NFS, Sendmail SNMP, TFTP, Iptables, BIND, Quagga, Syslog, Snort, Splunk Proficiency and SANs
Understanding of Unix tools RedHat Linux ES 3, 4, and 5
Some understanding of Cisco CatOS and IOS
Most employers will want candidates to know something about PHP, MYSQL, SAN and JBOSS.
A Linux software engineer will often be asked by an employer to performance tuning of systems and software, load new software and integrate it into existing systems, designing new systems with supporting instructions and trouble shoot system problems. Documentation can be a big part of the job, provide others with detailed notes of how and what you have done.