首先說明FreeBSD預設Shell是csh沒有ulimit命令，但C Shell有limit命令。如果你想使用ulimit命令可以安裝Bourne shell，Bash，Zsh
limit,ulimit比較
[neo@freebsd:~] limit cputime unlimited filesize unlimited datasize 32768MB stacksize 512MB coredumpsize unlimited memoryuse unlimited memorylocked unlimited maxproc 5547 descriptors 65536 sockbufsize unlimited vmemorysize unlimited NPTS unlimited SWAP unlimited [neo@freebsd:~] env | grep SHELL SHELL=/usr/local/bin/zsh [neo@freebsd:~] ulimit -a -t: cpu time (seconds) unlimited -f: file size (blocks) unlimited -d: data seg size (kbytes) 33554432 -s: stack size (kbytes) 524288 -c: core file size (blocks) unlimited -m: resident set size (kbytes) unlimited -l: locked-in-memory size (kb) unlimited -u: processes 5547 -n: file descriptors 65536 -N 9: socket buffer size (kb) unlimited -v: virtual memory size (kb) unlimited -N 11: unlimited -N 12: unlimited 在Freebsd上，你能使用sysctl命令：
以 nofile - max number of open files 為例，limit、ulimit、sysctl實現同樣的功能。
csh% limit descriptors unlimited 或者 csh% limit descriptors 4096 sh$ ulimit -n unlimited 或者 sh$ ulimit -n 4096 sysctl kern.maxfiles=65536 sysctl kern.maxfilesperproc=65536
寫入配置檔案 sysctl.conf
[neo@freebsd:~] cat /etc/sysctl.conf # $FreeBSD: src/etc/sysctl.conf,v 1.8.34.1.4.1 2010/06/14 02:09:06 kensmith Exp $ # # This file is read when going to multi-user and its contents piped thru # ``sysctl'' to adjust kernel values. ``man 5 sysctl.conf'' for details. # # Uncomment this to prevent users from seeing information about processes that # are being run under another UID. #security.bsd.see_other_uids=0 #vm.pmap.shpgperproc: 2000 #vm.pmap.pv_entry_max: 13338058 kern.ipc.shm_use_phys=1 kern.maxfiles=65536 kern.maxfilesperproc=65536 kern.ipc.somaxconn=2048 [neo@freebsd:~] /etc/rc.d/sysctl reload [neo@freebsd:~] sysctl -a | grep maxfiles kern.maxfiles: 65536 kern.maxfilesperproc: 65536