xref: /freebsd/usr.bin/fortune/datfiles/freebsd-tips (revision 2ccf8a827cce7e34e2063a3d33e5cce4b79799cc)
1This fortune brought to you by:
2$FreeBSD$
3%
4Any user that is a member of the wheel group can use "su -" to simulate
5a root login. You can add a user to the wheel group by editing /etc/group.
6		-- Konstantinos Konstantinidis <kkonstan@duth.gr>
7%
8By pressing "Scroll Lock" you can use the arrow keys to scroll backward
9through the console output.  Press "Scroll Lock" again to turn it off.
10Don't have a "Scroll Lock" key? The "Pause / Break" key acts alike.
11%
12Can't remember if you've installed a certain port or not? Try "pkg info
13-x port_name".
14%
15Ever wonder what those numbers after command names were, as in cat(1)?  It's
16the section of the manual the man page is in.  "man man" will tell you more.
17		-- David Scheidt <dscheidt@tumbolia.com>
18%
19Forget how to spell a word or a variation of a word? Use
20
21	look portion_of_word_you_know
22		-- Dru <genesis@istar.ca>
23%
24Forget what directory you are in? Type "pwd".
25		-- Dru <genesis@istar.ca>
26%
27Forget when Easter is? Try "ncal -e". If you need the date for Orthodox
28Easter, use "ncal -o" instead.
29		-- Dru <genesis@istar.ca>
30%
31FreeBSD is started up by the program 'init'.  The first thing init does when
32starting multiuser mode (ie, starting the computer up for normal use) is to
33run the shell script /etc/rc.  By reading /etc/rc and the /etc/rc.d/ scripts,
34you can learn a lot about how the system is put together, which again will
35make you more confident about what happens when you do something with it.
36%
37Handy bash(1) prompt:  PS1="\u@\h \w \!$ "
38		-- David Scheidt <dscheidt@tumbolia.com>
39%
40Having trouble using fetch through a firewall? Try setting the environment
41variable FTP_PASSIVE_MODE to yes, and see fetch(3) for more details.
42%
43If other operating systems have damaged your Master Boot Record, you can
44reinstall it with gpart(8). See
45"man gpart" for details.
46%
47If you accidentally end up inside vi, you can quit it by pressing Escape, colon
48(:), q (q), bang (!) and pressing return.
49%
50If you do not want to get beeps in X11 (X Windows), you can turn them off with
51
52	xset b off
53%
54If you have a CD-ROM drive in your machine, you can make the CD-ROM that is
55presently inserted available by typing 'mount /cdrom' as root.  The CD-ROM
56will be available under /cdrom/.  Remember to do 'umount /cdrom' before
57removing the CD-ROM (it will usually not be possible to remove the CD-ROM
58without doing this.)
59
60Note: This tip may not work in all configurations.
61%
62If you need a reminder to leave your terminal, type "leave +hhmm" where
63"hhmm" represents in how many hours and minutes you need to leave.
64		-- Dru <genesis@istar.ca>
65%
66If you need to ask a question on the FreeBSD-questions mailing list then
67
68	https://www.FreeBSD.org/doc/en_US.ISO8859-1/articles/\
69		freebsd-questions/index.html
70
71contains lots of useful advice to help you get the best results.
72%
73If you write part of a filename in tcsh,
74pressing TAB will show you the available choices when there
75is more than one, or complete the filename if there's only one match.
76%
77If you `set watch = (0 any any)' in tcsh, you will be notified when
78someone logs in or out of your system.
79%
80If you use the C shell, add the following line to the .cshrc file in your
81home directory to prevent core files from being written to disk:
82
83	limit coredumpsize 0
84		-- Dru <genesis@istar.ca>
85%
86If you want df(1) and other commands to display disk sizes in
87kilobytes instead of 512-byte blocks, set BLOCKSIZE in your
88environment to 'K'.  You can also use 'M' for Megabytes or 'G' for
89Gigabytes.  If you want df(1) to automatically select the best size
90then use 'df -h'.
91%
92If you want to play CDs with FreeBSD, a utility for this is already included.
93Type 'cdcontrol' then 'help' to learn more.  (You may need to set the CDROM
94environment variable in order to make cdcontrol want to start.)
95%
96If you'd like to keep track of applications in the FreeBSD ports tree, take a
97look at FreshPorts;
98
99	https://www.freshports.org/
100%
101In order to make fetch (the FreeBSD downloading tool) ask for
102username/password when it encounters a password-protected web page, you can set
103the environment variable HTTP_AUTH to 'basic:*'.
104%
105In order to search for a string in some files, use 'grep' like this:
106
107	 grep "string" filename1 [filename2 filename3 ...]
108
109This will print out the lines in the files that contain the string.  grep can
110also do a lot more advanced searches - type 'man grep' for details.
111%
112In order to support national characters for European languages in tools like
113less without creating other nationalisation aspects, set the environment
114variable LC_ALL to 'en_US.UTF-8'.
115%
116"man firewall" will give advice for building a FreeBSD firewall using ipfw(8).
117		-- David Scheidt <dscheidt@tumbolia.com>
118%
119"man hier" will explain the way FreeBSD filesystems are normally laid out.
120		-- David Scheidt <dscheidt@tumbolia.com>
121%
122Man pages are divided into section depending on topic.  There are 9 different
123sections numbered from 1 (General Commands) to 9 (Kernel Developer's Manual).
124You can get an introduction to each topic by typing
125
126	man <number> intro
127
128In other words, to get the intro to general commands, type
129
130	man 1 intro
131%
132"man ports" gives many useful hints about installing FreeBSD ports.
133%
134"man security" gives very good advice on how to tune the security of your
135FreeBSD system.
136%
137"man tuning" gives some tips how to tune performance of your FreeBSD system.
138		-- David Scheidt <dscheidt@tumbolia.com>
139%
140Need to do a search in a manpage or in a file you've sent to a pager? Use
141"/search_word". To repeat the same search, type "n" for next or "p" for
142previous.
143		-- Dru <genesis@istar.ca>
144%
145Need to find the location of a program? Use "locate program_name".
146		-- Dru <genesis@istar.ca>
147%
148Need to leave your terminal for a few minutes and don't want to logout?
149Use "lock -p". When you return, use your password as the key to unlock the
150terminal.
151		-- Dru <genesis@istar.ca>
152%
153Need to quickly empty a file? Use ": > filename".
154		-- Dru <genesis@istar.ca>
155%
156Need to quickly return to your home directory? Type "cd".
157		-- Dru <genesis@istar.ca>
158%
159Need to remove all those ^M characters from a DOS file? Try
160
161	tr -d \\r < dosfile > newfile
162		-- Originally by Dru <genesis@istar.ca>
163%
164Need to see the calendar for this month? Simply type "cal".  To see the
165whole year, type "cal -y".
166		-- Dru <genesis@istar.ca>
167%
168Need to see which daemons are listening for connection requests? Use
169"sockstat -4l" for IPv4, and "sockstat -l" for IPv4 and IPv6.
170		-- Dru <genesis@istar.ca>
171%
172Need to see your routing table? Type "netstat -rn". The entry with the G
173flag is your gateway.
174		-- Dru <genesis@istar.ca>
175%
176Nice bash prompt: PS1='(\[$(tput md)\]\t <\w>\[$(tput me)\]) $(echo $?) \$ '
177		-- Mathieu <mathieu@hal.interactionvirtuelle.com>
178%
179Over quota?  "du -sh * | sort -h " will give you a sorted list of your
180directory sizes.
181		-- David Scheidt <dscheidt@tumbolia.com>
182%
183nc(1) (or netcat) is useful not only for redirecting input/output to
184TCP or UDP connections, but also for proxying them with inetd(8).
185%
186sh (the default Bourne shell in FreeBSD) supports command-line editing.  Just
187``set -o emacs'' or ``set -o vi'' to enable it. Use "<TAB>" key to complete
188paths.
189%
190Simple tcsh prompt: set prompt = '%# '
191%
192The default editor in FreeBSD is vi, which is efficient to use when you have
193learned it, but somewhat user-unfriendly.  To use ee (an easier but less
194powerful editor) instead, set the environment variable EDITOR to /usr/bin/ee
195%
196Time to change your password? Type "passwd" and follow the prompts.
197		-- Dru <genesis@istar.ca>
198%
199To change an environment variable in /bin/sh use:
200
201	$ VARIABLE="value"
202	$ export VARIABLE
203%
204To change an environment variable in tcsh you use: setenv NAME "value"
205where NAME is the name of the variable and "value" its new value.
206%
207To clear the screen, use "clear". To re-display your screen buffer, press
208the scroll lock key and use your page up button. When you're finished,
209press the scroll lock key again to get your prompt back.
210		-- Dru <genesis@istar.ca>
211%
212You can press Ctrl-L while in the shell to clear the screen.
213%
214To determine whether a file is a text file, executable, or some other type
215of file, use
216
217	file filename
218		-- Dru <genesis@istar.ca>
219%
220To do a fast search for a file, try
221
222	 locate filename
223
224locate uses a database that is updated every Saturday (assuming your computer
225is running FreeBSD at the time) to quickly find files based on name only.
226%
227To erase a line you've written at the command prompt, use "Ctrl-U".
228		-- Dru <genesis@istar.ca>
229%
230To find out the hostname associated with an IP address, use
231
232	drill -x IP_address
233		-- Dru <genesis@istar.ca>
234%
235To obtain a neat PostScript rendering of a manual page, use ``-t'' switch
236of the man(1) utility: ``man -t <topic>''.  For example:
237
238	man -t grep > grep.ps	# Save the PostScript version to a file
239or
240	man -t printf | lp	# Send the PostScript directly to printer
241%
242To quickly create an empty file, use "touch filename".
243		-- Dru <genesis@istar.ca>
244%
245To read a compressed file without having to first uncompress it, use
246"zcat" or "zless" to view it. There is also "bzcat", "bzless", "xzcat"
247and "xzless".
248		-- Dru <genesis@istar.ca>
249%
250To save disk space in your home directory, compress files you rarely
251use with "gzip filename".
252		-- Dru <genesis@istar.ca>
253%
254To search for files that match a particular name, use find(1); for example
255
256	find / -name "*GENERIC*" -ls
257
258will search '/', and all subdirectories, for files with 'GENERIC' in the name.
259      	--  Stephen Hilton <nospam@hiltonbsd.com>
260%
261To see all of the directories on your FreeBSD system, type
262
263	find / -type d | less
264
265All the files?
266
267	find / -type f | less
268%
269To see how long it takes a command to run, type the word "time" before the
270command name.
271		-- Dru <genesis@istar.ca>
272%
273To see how much disk space is left on your UFS partitions, use
274
275	df -h
276		-- Dru <genesis@istar.ca>
277%
278To see the 10 largest files in a directory or on a UFS partition, use
279
280	du -h /partition_or_directory_name | sort -rh | head
281		-- Dru <genesis@istar.ca>
282%
283To see the IP addresses currently set on your active interfaces, type
284"ifconfig -u".
285		-- Dru <genesis@istar.ca>
286%
287To see the last 10 lines of a long file, use "tail filename". To see the
288first 10 lines, use "head filename". To see new lines as they're appended
289to a file, use "tail -f filename".
290		-- Dru <genesis@istar.ca>
291%
292To see the last time that you logged in, use lastlogin(8).
293		-- Dru <genesis@istar.ca>
294%
295To see the MAC addresses of the NICs on your system, type
296
297	ifconfig -a
298		-- Dru <genesis@istar.ca>
299%
300To see the output from when your computer started, run dmesg(8).  If it has
301been replaced with other messages, look at /var/run/dmesg.boot.
302		-- Francisco Reyes <lists@natserv.com>
303%
304Want colour in your directory listings?  Use "ls -G".  "ls -F" is also useful,
305and they can be combined as "ls -FG".
306%
307Want to find a specific port? Just type the following under /usr/ports
308or one of its subdirectories:
309
310	make search name=<port-name>
311    or
312	make search key=<keyword>
313%
314Want to know how many words, lines, or bytes are contained in a file? Type
315"wc filename".
316		-- Dru <genesis@istar.ca>
317%
318Want to see how much virtual memory you're using? Just type "swapinfo" to
319be shown information about the usage of your swap partitions.
320%
321Want to strip UTF-8 BOM(Byte Order Mark) from given files?
322
323	sed -e '1s/^\xef\xbb\xbf//' < bomfile > newfile
324%
325Want to use sed(1) to edit a file in place?  Well, to replace every 'e' with
326an 'o', in a file named 'foo', you can do:
327
328	sed -i.bak s/e/o/g foo
329
330And you'll get a backup of the original in a file named 'foo.bak', but if you
331want no backup:
332
333	sed -i '' s/e/o/g foo
334%
335When you've made modifications to a file in vi(1) and then find that
336you can't write it, type ``<ESC>!rm -f %'' then ``:w!'' to force the
337write
338
339This won't work if you don't have write permissions to the directory
340and probably won't be suitable if you're editing through a symbolic link.
341
342If you have sudo(8) installed and permissions to use it, type
343``<ESC>w ! sudo tee %'' to force a write.
344%
345You can adjust the volume of various parts of the sound system in your
346computer by typing 'mixer <type> <volume>'.  To get a list of what you can
347adjust, just type 'mixer'.
348%
349You can automatically download and install binary packages by doing
350
351	pkg install <package>
352
353This will also automatically install the packages that are dependencies
354for the package you install (ie, the packages it needs in order to work.)
355%
356You can change the video mode on all consoles by adding something like
357the following to /etc/rc.conf:
358
359	allscreens="80x30"
360
361You can use "vidcontrol -i mode | grep T" for a list of supported text
362modes.
363		-- Konstantinos Konstantinidis <kkonstan@duth.gr>
364%
365You can disable tcsh's terminal beep if you `set nobeep'.
366%
367You can install extra packages for FreeBSD by using the ports system.
368If you have installed it, you can download, compile, and install software by
369just typing
370
371	# cd /usr/ports/<category>/<portname>
372	# make install && make clean
373
374as root.  The ports infrastructure will download the software, change it so
375it works on FreeBSD, compile it, install it, register the installation so it
376will be possible to automatically uninstall it, and clean out the temporary
377working space it used.  You can remove an installed port you decide you do not
378want after all by typing
379
380	# cd /usr/ports/<category>/<portname>
381	# make deinstall
382
383as root.
384%
385You can look through a file in a nice text-based interface by typing
386
387	less filename
388%
389You can make a log of your terminal session with script(1).
390%
391You can often get answers to your questions about FreeBSD by searching in the
392FreeBSD mailing list archives at
393
394	http://freebsd.markmail.org
395%
396You can open up a new split-screen window in (n)vi with :N or :E and then
397use ^w to switch between the two.
398%
399You can permanently set environment variables for your shell by putting them
400in a startup file for the shell.  The name of the startup file varies
401depending on the shell - csh and tcsh uses .login, bash, sh, ksh and zsh use
402.profile.  When using bash, sh, ksh or zsh, don't forget to export the
403variable.
404%
405You can press Ctrl-D to quickly exit from a shell, or logout from a
406login shell.
407		-- Konstantinos Konstantinidis <kkonstan@duth.gr>
408%
409You can press up-arrow or down-arrow to walk through a list of
410previous commands in tcsh.
411%
412You can search for documentation on a keyword by typing
413
414	apropos keyword
415%
416You can `set autologout = 30' to have tcsh log you off automatically
417if you leave the shell idle for more than 30 minutes.
418%
419You can use aliases to decrease the amount of typing you need to do to get
420commands you commonly use.  Examples of fairly popular aliases include (in
421Bourne shell style, as in /bin/sh, bash, ksh, and zsh):
422
423	alias lf="ls -FA"
424	alias ll="ls -lA"
425	alias su="su -m"
426
427In csh or tcsh, these would be
428
429	alias lf ls -FA
430	alias ll ls -lA
431	alias su su -m
432
433To remove an alias, you can usually use 'unalias aliasname'.  To list all
434aliases, you can usually type just 'alias'.
435%
436You can use /etc/make.conf to control the options used to compile software
437on this system.  Example entries are in
438/usr/share/examples/etc/make.conf and in make.conf(5).
439For options that are set for building FreeBSD's kernel and its world, see
440src.conf(5).
441%
442You can use "pkg info" to see a list of packages you have installed.
443%
444You can use the 'fetch' command to retrieve files over ftp, http or https.
445
446	 fetch https://www.FreeBSD.org/index.html
447
448will download the front page of the FreeBSD web site.
449%
450You can use "whereis" to search standard binary, manual page and source
451directories for the specified programs. This can be particularly handy
452when you are trying to find where in the ports tree an application is.
453
454Try "whereis firefox" and "whereis whereis".
455		-- Konstantinos Konstantinidis <kkonstan@duth.gr>
456%
457Want to run the same command again?
458In many shells (e.g., tcsh, zsh, bash) you can type "!!".
459%
460Want to go the directory you were just in?
461Type "cd -"
462%
463Can't delete /usr/obj? Enter "chflags -R noschg /usr/obj" to remove the
464system immutable flag for all files in /usr/obj.
465
466		-- Lars Engels <lme@FreeBSD.org>
467%
468Want to list all files of an installed package? Enter
469"pkg info -l packagename".
470
471		-- Lars Engels <lme@FreeBSD.org>
472%
473Are you looking for a package? Search for it with
474"pkg search part_of_package_name"
475
476		-- Lars Engels <lme@FreeBSD.org>
477%
478If you want to recursively copy a directory preserving file and directory
479attributes use
480"cp -a source target"
481
482		-- Lars Engels <lme@FreeBSD.org>
483%
484Do you wonder what a terminal program is doing at the moment? dd(1) does not
485show any throughput? Hit "^T" (Control + t) to send SIGINFO to the process
486and see what it is doing.
487
488		-- Lars Engels <lme@FreeBSD.org>
489%
490Do you want to know which version of FreeBSD you are running? Enter
491"freebsd-version -ku" to display kernel and userland version.
492
493		-- Lars Engels <lme@FreeBSD.org>
494%
495If you want to end one or more processes at a time using a regular expression
496enter "pkill regex".
497
498		-- Lars Engels <lme@FreeBSD.org>
499%
500Do you want to run a program directly after some other process has ended? Use
501"pwait pid && new_program"
502
503		-- Lars Engels <lme@FreeBSD.org>
504%
505When you want your users to be able to reboot or shutdown FreeBSD, add them
506to the group "operator" and they are allowed to use shutdown(8) and poweroff(8).
507
508		-- Lars Engels <lme@FreeBSD.org>
509%
510If you need to create a FAT32 formatted USB thumb drive, find out its devicename
511running dmesg(8) after inserting it. Then create an MBR schema, a single slice and
512format it:
513
514# gpart create -s MBR ${devicename}
515# gpart add -t fat32 ${devicename}
516# newfs_msdos -F 32 -L thumbdrive ${devicename}s1
517
518		-- Lars Engels <lme@FreeBSD.org>
519%
520If you want to get a sorted list of all services that are started when FreeBSD boots,
521enter "service -e".
522
523		-- Lars Engels <lme@FreeBSD.org>
524%
525To easily configure your installed FreeBSD use bsdconfig(8).
526
527		-- Lars Engels <lme@FreeBSD.org>
528%
529After you compiled and installed a new version of FreeBSD, use etcupdate(8) to merge
530configuration updates.
531Run "etcupdate extract" once when your sources match your running system, then run
532"etcupdate" after every upgrade and "etcupdate resolve" to resolve any conflicts.
533
534		-- Lars Engels <lme@FreeBSD.org>
535%
536Do you want to do a binary upgrade of your running FreeBSD installation? Use freebsd-update(8).
537
538To install updates and patches for the running branch use
539# freebsd-update fetch install
540
541To upgrade to a newer release use
542# freebsd-update upgrade -r ${name_of_release}
543
544		-- Lars Engels <lme@FreeBSD.org>
545%
546To run rc scripts in /etc/rc.d and /usr/local/etc/rc.d use service(8).
547Run "service ${name_of_rc_script} start" to start a daemon and
548"service ${name_of_rc_script} stop" to stop it.
549
550		-- Lars Engels <lme@FreeBSD.org>
551%
552If you don't want to edit /etc/rc.conf directly, use sysrc(8) to add and remove entries.
553Use "sysrc name=value" to add an entry and "sysrc -x name" to delete an entry.
554
555		-- Lars Engels <lme@FreeBSD.org>
556%
557You can upload the dmesg of your system to help developers get an overview of commonly
558used hardware and peripherals for FreeBSD. Use the curl package to upload it like this:
559curl -v -d "nickname=$USER" -d "description=FreeBSD/$(uname -m) on \
560$(kenv smbios.system.maker) $(kenv smbios.system.product)" -d "do=addd" \
561--data-urlencode 'dmesg@/var/run/dmesg.boot' http://dmesgd.nycbug.org/index.cgi
562%
563Want to know how much memory (in bytes) your machine has installed? Let
564sysctl(8) tell you with the following command:
565
566sysctl hw.realmem
567
568The realmem value is memory before the kernel and modules are loaded, whereas
569hw.physmem is what is left after they were loaded.
570
571The number of active CPUs is displayed using this command:
572
573sysctl hw.ncpu
574
575		-- Benedict Reuschling <bcr@FreeBSD.org>
576%
577When using ZFS as the file system the "df" command is reporting the pool size
578and not file system sizes. It also does not know about descendent ZFS
579datasets, snapshots, quotas, and reservations with their individual space usage.
580Use the built-in "zfs list" command to get a better overview of space usage:
581
582zfs list -o space
583
584		-- Benedict Reuschling <bcr@FreeBSD.org>
585%
586To learn more about what your system is doing, take a look at systat(1). For
587example, to get various of statistics related to virtual memory usage, process
588scheduling, device interrupts, system name translation caching, and disk I/O,
589enter the following:
590
591systat -vmstat
592
593Other values are icmp, icmp6, ifstat, iostat, ip, ip6, netstat, pigs, sctp,
594swap, tcp, or zarc. You can switch between displays using :<display> and exit
595back to your shell by typing
596
597:quit
598
599		-- Benedict Reuschling <bcr@FreeBSD.org>
600%
601To set a quota of 10 GB for the user named foo on a ZFS dataset, run the
602following command:
603
604# zfs set userquota@foo=10G pool/home/foo
605
606The zfs userspace command can display the quota and current space usage:
607
608# zfs userspace pool/home/foo
609
610To unset a quota, assign "none" as the value.
611		-- Benedict Reuschling <bcr@FreeBSD.org>
612%
613ZFS can display I/O statistics for a given pool using the iostat subcommand.
614By default, it will display one line of current activity.  To display stats
615every 5 seconds run the following command (cancel with CTRL+C):
616
617zpool iostat 5
618
619To view individual disk activities, specify the -v parameter:
620
621zpool iostat -v
622
623Of course, both can be combined. For more options, see zpool(8).
624		-- Benedict Reuschling <bcr@FreeBSD.org>
625%
626FreeBSD's top(1) utility displays CPU statistics by default.
627To display I/O activity for each process instead, run top like this:
628
629top -m io
630
631		-- Benedict Reuschling <bcr@FreeBSD.org>
632%
633ZFS keeps a history of commands run against a specific pool using the
634history subcommand to zpool:
635
636zpool history
637
638More details are available using the -i and -l parameters. Note that ZFS
639will not keep the complete pool history forever and will remove older
640events in favor of never ones.
641		-- Benedict Reuschling <bcr@FreeBSD.org>
642%
643To display the compression ratio for the ZFS dataset /var/log on the pool
644mypool, run the following command:
645
646zfs get refcompressratio mypool/var/log
647
648The refcompressratio will only display the compression ratio for that specific
649dataset, not the descendant datasets. To include the child datasets, the
650command looks like this:
651
652zfs get compressratio mypool/var
653
654		-- Benedict Reuschling <bcr@FreeBSD.org>
655%
656You can limit the depth of the displayed datasets in the "zfs list" output
657using the -d parameter. To display only the first level of datasets below
658mypool/usr and not the ones deeper than those, run this command:
659
660zfs list -d 1 mypool/usr
661
662		-- Benedict Reuschling <bcr@FreeBSD.org>
663%
664The "zfs list" command can be filtered in multiple ways. To display just
665the dataset name, use the -o parameter:
666
667zfs list -o name mypool/usr
668
669More columns and their order can be defined by separating them with commas:
670
671zfs list -o mountpoint,name,avail
672
673		-- Benedict Reuschling <bcr@FreeBSD.org>
674%
675The output of "zfs list" can be sorted by a specific column using -s.  To
676sort the datasets by the "used" column in ascending order, run this command:
677
678zfs list -s used
679
680To sort in descending order instead, use -S:
681
682zfs list -S used
683
684		-- Benedict Reuschling <bcr@FreeBSD.org>
685%
686To make the "zfs list" output more script-friendly, you can suppress the
687output of the headers for each column by passing the -H parameter:
688
689zfs list -H
690
691Another helpful option for script writers is -p, which displays the numbers
692in non-rounded, exact values:
693
694zfs list -p
695
696		-- Benedict Reuschling <bcr@FreeBSD.org>
697%
698Before deleting a dataset or snapshot, perform a dry run using the -n
699parameter. This is to make sure you really want to delete just that
700dataset/snapshot and not any dependent ones. ZFS will display the resulting
701action when -n is combined with the -v option without actually performing
702it:
703
704zfs destroy -nrv mypool@mysnap
705
706Once you are sure this is exactly what you intend to do, remove the -n
707parameter to execute the destroy operation.
708		-- Benedict Reuschling <bcr@FreeBSD.org>
709%
710You can delete a range of ZFS snapshots (a-z) in multiple ways.
711The following will delete d and all earlier snapshots:
712
713zfs destroy mypool/data@%d
714
715To delete d and all later snapshots:
716
717zfs destroy mypool/data@d%
718
719To delete all dataset snapshots:
720
721zfs destroy mypool/data@%
722
723Make sure to let ZFS perform a dry run (-n option) first and display (-v) what
724it would do to confirm that the delete operation is removing exactly what you
725intended.
726		-- Benedict Reuschling <bcr@FreeBSD.org>
727%
728To set a custom ZFS property on the mypool pool, you need to provide it
729using the "key1:key2=value" syntax, where the colon (:) is used as the
730separator and identifier from the built-in ZFS properties:
731
732# zfs set warranty:expires=2038-01-19 mypool
733
734The custom property is applied to all datasets and can be queried like any
735built-in properties using zfs get:
736
737zfs get warranty:expires mypool
738
739To reset the value of a custom property, use the inherit subcommand:
740
741# zfs inherit warranty:expires mypool
742
743Removing a custom property from a pool is done using the -r flag to the
744"zfs inherit" command:
745
746# zfs inherit -r warranty:expires mypool
747
748		-- Benedict Reuschling <bcr@FreeBSD.org>
749%
750To delete a range of ZFS snapshots, use the % (percent) character after the
751full path to the first snapshot that should be included. For example, to
752simulate deleting snapshots a through (including) d, use this command:
753
754# zfs destroy -rvn mypool/tmp@a%d
755
756Once you are sure that this is what you want, remove the -n option:
757
758# zfs destroy -rv mypool/tmp@a%d
759
760		-- Benedict Reuschling <bcr@FreeBSD.org>
761%
762You can prevent the removal of a ZFS snapshot by using the hold subcommand.
763For example, to prevent the snapshot called milestone from deletion, run the
764following command:
765
766# zfs hold milestone_hold mypool/projects@my_milestone
767
768The "zfs holds" command will list all current snapshots that are protected
769this way (-r for a recursive list):
770
771# zfs holds -r mypool
772
773The TIMESTAMP column in the output of the above command is from when the
774hold was created, not the snapshot it holds. The "zfs destroy" command will
775echo a "dataset is busy" message on the console when it encounters a hold.
776Use "zfs release" to release the hold on the snapshot:
777
778# zfs release milestone_hold mypool/projects@my_milestone
779
780		-- Benedict Reuschling <bcr@FreeBSD.org>
781%
782A user "sender" needs the following permissions set to send a ZFS dataset:
783
784# zfs allow -u sender send,snapshot txpool
785
786On the receiving side, the user "receiver" requires these permissions:
787
788# zfs allow -u receiver compression,mountpoint,mount,create,receive rxpool
789
790		-- Benedict Reuschling <bcr@FreeBSD.org>
791%
792Don't let your zpool fill up completely by creating a dataset with
793reservation.
794
795# zfs create -o refreservation=<5% of total pool space> <poolname>/reserved
796
797You can always shrink the reserve if you need the space, but your pool will
798always have space left this way.
799
800		-- Benedict Reuschling <bcr@FreeBSD.org>
801%
802