FreeBSD Cheat Sheet for Linux Admins

Fr 29 August 2025
FreeBSD
#freebsd, #linux, #sysadmin

Hardware Information

Task	FreeBSD	Linux
List PCI devices	`pciconf -lv`	`lspci -v`
List USB devices	`usbconfig`	`lsusb`
Show CPU info	`sysctl hw.model` or `dmesg \\| grep CPU`	`cat /proc/cpuinfo` or `lscpu`
Show memory info	`sysctl hw.physmem` or `top`	`free -h` or `cat /proc/meminfo`
Show kernel modules	`kldstat`	`lsmod`
Load kernel module	`kldload module_name`	`modprobe module_name`
Unload kernel module	`kldunload module_name`	`modprobe -r module_name`

Disk and Storage Management

Task	FreeBSD	Linux
List all disks	`geom disk list`	`lsblk` or `fdisk -l`
Show disk partitions	`gpart show`	`fdisk -l` or `parted -l`
Show disk usage	`df -h`	`df -h`
Show mounted filesystems	`mount`	`mount` or `findmnt`
Check filesystem	`fsck`	`fsck`
Show SMART data	`smartctl -a /dev/ada0`	`smartctl -a /dev/sda`
List ZFS pools	`zpool list`	`zpool list` (if ZFS installed)
Show ZFS datasets	`zfs list`	`zfs list` (if ZFS installed)

Network Commands

Task	FreeBSD	Linux
Show network interfaces	`ifconfig`	`ip addr` or `ifconfig`
Configure interface	`ifconfig em0 inet 192.168.1.10`	`ip addr add 192.168.1.10/24 dev eth0`
Show routing table	`netstat -rn`	`ip route` or `route -n`
Add static route	`route add default 192.168.1.1`	`ip route add default via 192.168.1.1`
Show ARP table	`arp -a`	`arp -a` or `ip neigh`
Clear ARP entry	`arp -d hostname`	`arp -d hostname` or `ip neigh del`
Show network statistics	`netstat -s`	`netstat -s` or `ss -s`
Show listening ports	`sockstat -l` or `netstat -an`	`ss -tuln` or `netstat -tuln`
Show all open ports/connections	`sockstat`	`ss -tuan` or `netstat -tuan`
Packet capture	`tcpdump -i em0`	`tcpdump -i eth0`

Process Management

Task	FreeBSD	Linux
List all processes	`ps aux`	`ps aux`
Process tree	`pstree`	`pstree` or `ps axjf`
Real-time process view	`top`	`top` or `htop`
Kill process	`kill PID`	`kill PID`
Show open files by process	`fstat`	`lsof`
Show process using port	`sockstat -p 80`	`lsof -i :80` or `ss -tulpn \\| grep :80`

Package Management

Task	FreeBSD	Linux (varies by distro)
Install package	`pkg install package_name`	`apt install` / `yum install` / `dnf install`
Remove package	`pkg delete package_name`	`apt remove` / `yum remove` / `dnf remove`
Update package list	`pkg update`	`apt update` / `yum check-update`
Upgrade packages	`pkg upgrade`	`apt upgrade` / `yum upgrade` / `dnf upgrade`
Search packages	`pkg search keyword`	`apt search` / `yum search` / `dnf search`
Show package info	`pkg info package_name`	`apt show` / `yum info` / `dnf info`
List installed packages	`pkg info`	`dpkg -l` / `rpm -qa`

System Services

Task	FreeBSD	Linux (systemd)
Start service	`service servicename start`	`systemctl start servicename`
Stop service	`service servicename stop`	`systemctl stop servicename`
Restart service	`service servicename restart`	`systemctl restart servicename`
Service status	`service servicename status`	`systemctl status servicename`
Enable at boot	`sysrc servicename_enable="YES"`	`systemctl enable servicename`
Disable at boot	`sysrc servicename_enable="NO"`	`systemctl disable servicename`
List all services	`service -e`	`systemctl list-units --type=service`

Firewall

Task	FreeBSD (pf/ipfw)	Linux (iptables/nftables)
Show rules (pf)	`pfctl -sr`	`iptables -L -n -v`
Show rules (ipfw)	`ipfw list`	`nft list ruleset`
Enable firewall (pf)	`pfctl -e`	`systemctl start firewalld`
Disable firewall (pf)	`pfctl -d`	`systemctl stop firewalld`
Reload rules (pf)	`pfctl -f /etc/pf.conf`	`iptables-restore < /etc/iptables/rules.v4`

System Information

Task	FreeBSD	Linux
System uptime	`uptime`	`uptime`
Kernel version	`uname -a` or `freebsd-version`	`uname -a`
Show all sysctl variables	`sysctl -a`	`sysctl -a`
Show system messages	`dmesg`	`dmesg` or `journalctl -k`
Show system logs	`tail /var/log/messages`	`journalctl` or `tail /var/log/syslog`

User Management

Task	FreeBSD	Linux
Add user	`adduser` or `pw useradd username`	`useradd username` or `adduser username`
Delete user	`rmuser` or `pw userdel username`	`userdel username`
Modify user	`pw usermod username`	`usermod username`
Change password	`passwd username`	`passwd username`
Show logged-in users	`who` or `w`	`who` or `w`

File Systems

Task	FreeBSD	Linux
Mount filesystem	`mount /dev/ada0p2 /mnt`	`mount /dev/sda2 /mnt`
Unmount filesystem	`umount /mnt`	`umount /mnt`
Create UFS filesystem	`newfs /dev/ada0p2`	N/A (UFS not common)
Create ext4 filesystem	N/A	`mkfs.ext4 /dev/sda2`
Check disk space	`du -sh /path`	`du -sh /path`

ZFS Commands (Same on FreeBSD and Linux with ZFS)

Pool Operations

Task	Command	Example
List all pools	`zpool list`	`zpool list`
Show pool status	`zpool status`	`zpool status tank`
Show pool history	`zpool history`	`zpool history tank`
Show pool I/O statistics	`zpool iostat`	`zpool iostat -v 2` (every 2 seconds)
Create simple pool	`zpool create`	`zpool create tank /dev/ada1`
Create mirror pool	`zpool create`	`zpool create tank mirror /dev/ada1 /dev/ada2`
Create RAIDZ pool	`zpool create`	`zpool create tank raidz /dev/ada1 /dev/ada2 /dev/ada3`
Add disk to pool	`zpool add`	`zpool add tank /dev/ada4`
Replace disk in pool	`zpool replace`	`zpool replace tank /dev/ada1 /dev/ada4`
Remove device from pool	`zpool remove`	`zpool remove tank /dev/ada4`
Scrub pool (check integrity)	`zpool scrub`	`zpool scrub tank`
Stop scrub	`zpool scrub -s`	`zpool scrub -s tank`
Clear pool errors	`zpool clear`	`zpool clear tank`
Export pool	`zpool export`	`zpool export tank`
Import pool	`zpool import`	`zpool import tank`
List importable pools	`zpool import`	`zpool import` (without pool name)
Upgrade pool	`zpool upgrade`	`zpool upgrade tank`
Set pool property	`zpool set`	`zpool set autoreplace=on tank`
Get pool properties	`zpool get`	`zpool get all tank`

Dataset (Filesystem) Operations

Task	Command	Example
List all datasets	`zfs list`	`zfs list`
List with specific properties	`zfs list`	`zfs list -o name,used,avail,mountpoint`
List snapshots	`zfs list -t snapshot`	`zfs list -t snapshot`
Create dataset	`zfs create`	`zfs create tank/home/user`
Destroy dataset	`zfs destroy`	`zfs destroy tank/old_data`
Destroy dataset and children	`zfs destroy -r`	`zfs destroy -r tank/old_data`
Set dataset property	`zfs set`	`zfs set compression=lz4 tank/home`
Get dataset properties	`zfs get`	`zfs get all tank/home`
Set quota	`zfs set quota=`	`zfs set quota=10G tank/home/user`
Set reservation	`zfs set reservation=`	`zfs set reservation=5G tank/database`
Mount dataset	`zfs mount`	`zfs mount tank/home`
Unmount dataset	`zfs unmount`	`zfs unmount tank/home`
Show mounted ZFS filesystems	`zfs mount`	`zfs mount` (without arguments)

Snapshot Operations

Task	Command	Example
Create snapshot	`zfs snapshot`	`zfs snapshot tank/home@backup-2024`
Create recursive snapshot	`zfs snapshot -r`	`zfs snapshot -r tank/home@daily-2024`
List snapshots	`zfs list -t snapshot`	`zfs list -t snapshot -r tank/home`
Rollback to snapshot	`zfs rollback`	`zfs rollback tank/home@backup-2024`
Destroy snapshot	`zfs destroy`	`zfs destroy tank/home@old-backup`
Rename snapshot	`zfs rename`	`zfs rename tank/home@old tank/home@archived`
Clone snapshot	`zfs clone`	`zfs clone tank/home@backup tank/home_clone`
Show snapshot disk usage	`zfs list -o space`	`zfs list -r -o space tank`

Send/Receive (Replication)

Task	Command	Example
Send snapshot	`zfs send`	`zfs send tank/home@backup > /backup/home.zfs`
Send incremental	`zfs send -i`	`zfs send -i @snap1 tank/home@snap2 > incremental.zfs`
Receive snapshot	`zfs receive`	`zfs receive tank/home_restore < /backup/home.zfs`
Send over SSH	`zfs send \\| ssh`	`zfs send tank/home@backup \\| ssh user@host zfs receive tank/backup`
Dry-run receive	`zfs receive -n`	`zfs receive -n tank/test < backup.zfs`
Send with progress	`zfs send -v`	`zfs send -v tank/home@backup > backup.zfs`

Common Property Settings

Task	Command	Example
Enable compression	`zfs set compression=`	`zfs set compression=lz4 tank/data`
Enable deduplication	`zfs set dedup=`	`zfs set dedup=on tank/backup`
Set record size	`zfs set recordsize=`	`zfs set recordsize=1M tank/media`
Enable encryption	`zfs create -o encryption=`	`zfs create -o encryption=on -o keyformat=passphrase tank/secure`
Set access time	`zfs set atime=`	`zfs set atime=off tank/database`
Set sync behavior	`zfs set sync=`	`zfs set sync=disabled tank/temp`
Enable case insensitivity	`zfs set casesensitivity=`	`zfs create -o casesensitivity=insensitive tank/windows`

Monitoring and Maintenance

Task	Command	Example
Show pool I/O stats	`zpool iostat`	`zpool iostat -v tank 2`
Show ARC stats (FreeBSD)	`sysctl kstat.zfs.misc.arcstats`	`sysctl kstat.zfs.misc.arcstats.size`
Show ARC stats (Linux)	`arc_summary`	`arc_summary` or `cat /proc/spl/kstat/zfs/arcstats`
Check pool health	`zpool status -x`	`zpool status -x` (only shows problems)
Show pool events	`zpool events`	`zpool events -v`
Estimated scrub time	`zpool status`	`zpool status` (during scrub)
Show compression ratio	`zfs get compressratio`	`zfs get compressratio tank/data`
Show space usage by type	`zfs list -o space`	`zfs list -r -o space tank`

Useful One-Liners

# Find largest datasets
zfs list -o name,used -s used

# Show all snapshots sorted by creation
zfs list -t snapshot -o name,creation -s creation

# Calculate total snapshot space
zfs list -t snapshot -o used -p | awk '{sum+=$1} END {print sum/1024/1024/1024 " GB"}'

# Show datasets with compression disabled
zfs get -r compression tank | grep -v "lz4\|gzip\|zle"

# Monitor pool I/O in real-time
zpool iostat -v 1

# Show properties that differ from defaults
zfs get all tank | grep -v default

# Quick backup to remote system
zfs snapshot tank/important@$(date +%Y%m%d) && \
zfs send tank/important@$(date +%Y%m%d) | ssh backup-server zfs receive tank/backup-2024

Quick Tips

Device naming: FreeBSD uses different naming conventions (ada0 for SATA, da0 for SCSI/USB) vs Linux (sda, sdb, etc.)
Network interfaces: FreeBSD names interfaces by driver (em0, re0, bge0) while Linux traditionally used eth0, eth1 (now often uses predictable names like enp0s3)
Configuration files: FreeBSD centralizes many configs in /etc/rc.conf while Linux distributes them across various files
Manual pages: Both use man command, but FreeBSD’s man pages are often more comprehensive
Ports vs Packages: FreeBSD has both ports (source) and packages (binary), while Linux typically uses one package manager per distribution
ZFS: While native to FreeBSD, ZFS on Linux (ZoL) has reached feature parity. Commands are identical, but kernel module loading differs (kldload zfs on FreeBSD vs modprobe zfs on Linux)