List 20 largest files (larger than 5 MB) sorted by megabytes:

 find / -type f -size +10000 -print0 | xargs -0 du -m | sort -nr | head -20
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You can keep specific rc.conf configurations in individual files
under /etc/rc.conf.d/ where each file is named after the $name of
the rc.d script. Some configurations may have different names than
the script; see the $name variable to check.
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You can see the total used buffers in megabytes with:

 vmstat -s | awk '
/ bytes per page$/ { bpp = $1 }
/ cached file pages$/ { cfp = $1 }
/ cached executable pages$/ { cep = $1 }
END { print((cfp + cep) * bpp / 1024 / 1024); }'
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You can view a value of a variable in pkgsrc by using the show-var
target, for example:

 make show-var VARNAME=MAINTAINER
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You can view the basic order of your rc.d scripts with:

 rcorder /etc/rc.d/*
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You can ask questions about NetBSD at the netbsd-users@NetBSD.org
mailing list. Be sure to clearly explain your problem, what you
tried, what results you had, and what you expected.
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You can view your non-default Postfix settings with:

 postconf -n
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To report about installed packages with known vulnerabilities,
fetch the latest pkg-vulnerabilities file as the superuser with:

 download-vulnerability-list

And then run:

 audit-packages
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The following shows an example of temporarily adding 10MB more swap
space for virtual memory:

 dd if=/dev/zero of=/root/swapfile bs=1024 count=10000
 swapctl -a /root/swapfile
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If your console ever gets broken, you can try resetting it to its
initial state with:

 printf "\033c
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If you installed a package, but don't know what the software is
called or what executables, to run use the pkg_add with the -L
switch to list the package's files and search for /bin:

 pkg_add -L PACKAGE-NAME | grep /bin
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A new user can be added by using the useradd tool with the -m switch
to create the home directory. Then set the password. For example:

 useradd -m susan
 passwd susan
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To modify user account information use the chpass or usermod tools.
If you need to edit the user database directly, use the vipw command.
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You can temporarily start the SSH server by running the following
as root:

 /etc/rc.d/sshd onestart
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Several IP Filter and ipnat examples are available in the
/usr/share/examples/ipf/ directory.
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Want to dual boot using a bluetooth mouse or keyboard? Use btkey(1)
to store the link key in the hardware.
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If you are having trouble connecting to a remote bluetooth device,
try the btconfig(8) inquiry command. The kernel will retain some
clock offset information that may help.
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You can download files via HTTP using the ftp(1) command; for example:

 ftp http://www.NetBSD.org/images/NetBSD.png
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The mtree(8) tool can be used to check permissions, ownerships,
file changes, and more when compared against a specification. For
example to check directory ownership and permissions for standard
NetBSD directories, run:

  /usr/sbin/mtree -e -p / -f /etc/mtree/NetBSD.dist
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If you need reminders on your console to leave, use the leave(1)
tool. For example to receive reminders to leave in one hour:

  leave +0100
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To stop non-superuser logins until next boot, as root:

  touch /etc/nologin
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When extracting distribution tar sets, be sure to use the pax -pe
option or the tar -p switch to preserve the user and group and file
modes (including setuid and setgid). This is needed, for example,
so su(1) will work after extracting the base.tgz set.
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Math can be done within the sh(1) and ksh(1) shells or with expr(1),
dc(1), bc(1), or awk(1). Here are some simple examples:

 echo $((431 * 79))
 expr 60 \* 60 \* 24 \* 7
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