Gotchas, Linux

Things you should know if you're coming to FreeBSD from Linux

1. The kernels are different -- monolithic instead of microkernels, although FreeBSD does allow dynamic loading of modules (see kldstat, kldload, kldunload.)
2. No iptables/netfilter: ipfw packet filter takes it's place, but you have to recompile your kernel to include it
3. No /proc tree. If you're used to banging around /proc to find system info, man sysctl. If you installed linux-compatibility, see /usr/compat/linux/proc
4. You don't have to compile everything from ports, it's usually better for your particular system if you do. See pkg_add and the other pkg tools.
5. If in doubt, read the Handbook (or ask here).
6. Different filesystems: linux uses ext2/ext3/reiserfs by default (usually) and FreeBSD uses UFS. Yes, it does journaling.
7. Java's a tough nut to install. Deal.
8. /stand/sysinstall will be quite useful to you at first.
9. bash is not the default shell, csh or tcsh is. If you want to change that, see chsh.
10. Most linux distros use vim, FreeBSD uses nvi by default. You can change this if it matters to you. Use /usr/ports/editors/vim-lite if you do not want to install the X windowing system else use /usr/ports/editors/vim.
11. Your NIC is no longer eth0 or eth0 or whatever. FreeBSD names it's interfaces by the driver they use; you'll see rl0, ed0, hme0, etc.
12. /etc/mtab doesn't show you mounts. mount and df do.
13. Your hard disks are no longer /dev/hda or /dev/sda. Now they are /dev/ad0s1a. See partitions.
14. devinfo and swapinfo will do a lot of sysctl magic for you.
15. Software RAID? See vinum.
16. Bandwidth limiting/traffic shaping? See dummynet
17. Disk encryption? [It's in the Handbook]
18. You need to be a member of the wheel group to allow you to su to root.