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 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