chmod u+x /var/spool/exim

To print all packets arriving at or departing from sundown:

tcpdump host sundown

To print traffic between helios and either hot or ace:

tcpdump host helios and \( hot or ace \)

To print all IP packets between ace and any host except helios:

 tcpdump ip host ace and not helios

To print all traffic between local hosts and hosts at Berkeley:

tcpdump net ucb-ether

To print all ftp traffic through internet gateway snup: (note that the expression is quoted to prevent the shell from (mis-)interpreting the parentheses):

 tcpdump 'gateway snup and (port ftp or ftp-data)'

To print traffic neither sourced from nor destined for local hosts (if you gateway to one other net, this stuff should never make it onto your local net).

 tcpdump ip and not net localnet

To print the start and end packets (the SYN and FIN packets) of each TCP conversation that involves a non-local host.

tcpdump 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet'

To print all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain data, not, for example, SYN and FIN packets and ACK-only packets. (IPv6 is left as an exercise for the reader.)

 tcpdump 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'

To print IP packets longer than 576 bytes sent through gateway snup:

tcpdump 'gateway snup and ip[2:2] > 576'

To print IP broadcast or multicast packets that were not sent via Ethernet broadcast or multicast:

 tcpdump 'ether[0] & 1 = 0 and ip[16] >= 224'

To print all ICMP packets that are not echo requests/replies (i.e., not ping packets):

tcpdump 'icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply'

$ ~ dmesg | grep microcode
[    0.000000] CPU0 microcode updated early to revision 0x1c, date = 2014-07-03
[    0.266118] CPU2 microcode updated early to revision 0x1c, date = 2014-07-03
[    0.691853] microcode: CPU0 sig=0x306c3, pf=0x10, revision=0x1c
[    0.691868] microcode: CPU1 sig=0x306c3, pf=0x10, revision=0x1c
[    0.691884] microcode: CPU2 sig=0x306c3, pf=0x10, revision=0x1c
[    0.691903] microcode: CPU3 sig=0x306c3, pf=0x10, revision=0x1c
[    0.692003] microcode: Microcode Update Driver: v2.00 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
[  906.261110] CPU1 microcode updated early to revision 0x1c, date = 2014-07-03
[  906.276502] CPU2 microcode updated early to revision 0x1c, date = 2014-07-03

$ ~ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 60
Model name:            Intel(R) Core(TM) i5-4200M CPU @ 2.50GHz
Stepping:              3
CPU MHz:               3068.847
CPU max MHz:           3100.0000
CPU min MHz:           800.0000
BogoMIPS:              4990.89
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

 sudo systemctl restart netctl-auto@wlp4s0.service

genues
Хм, а у меня вроде всё ок:

journalctl -b | grep swap

$ ~ dmesg | grep swap
[    7.709753] Adding 16777212k swap on /dev/sda2.  Priority:-1 extents:1 across:16777212k FS

$ ~ journalctl -b | grep swap
Nov 12 10:39:56 edge kernel: Adding 16777212k swap on /dev/sda2.  Priority:-1 extents:1 across:16777212k FS

$ ~ systemctl status dev-sda2.swap
● dev-sda2.swap - Swap Partition
   Loaded: loaded (/run/systemd/generator.late/dev-sda2.swap)
   Active: active since Wed 2014-11-12 10:39:54 EET; 11min ago
     What: /dev/sda2
     Docs: man:systemd-gpt-auto-generator(8)
  Process: 280 ExecActivate=/sbin/swapon /dev/sda2 (code=exited, status=0/SUCCESS)

$ ~ swapon -s
Filename				Type		Size	Used	Priority
/dev/sda2                              	partition	16777212	0	-1

$ ~ free -h
              total        used        free      shared  buff/cache   available
Mem:            15G        300M         15G         42M        248M         15G
Swap:           15G          0B         15G

link to this item - Bugzilla: #1017509
Error messages about swap activation if swap is on a plain partition on a GPT disk

If your swap device is a plain partition (not LVM-backed) on a GPT-labelled disk, it appears that systemd has some trouble activating this, and you will notice errors in your system log at each boot, related to swap activation. However, testing indicates that the swap device is ultimately activated successfully. This issue is unlikely to cause any real problems, we note it purely to explain why you may see these errors in the system log. You can run the command swapon without any parameters if you wish to check that the partition has been successfully activated.

$ ~ gdisk -l /dev/sda | grep -i swap
   2          739328        34293759   16.0 GiB    8200  Linux swap

$ ~ dmesg | grep swap
[    8.120123] systemd[1]: dev-disk-by\x2duuid-da08bb2e\x2d69dc\x2d4a28\x2db994\x2d2f3183d2950b.swap swap process exited, code=exited status=255
[    8.120495] systemd[1]: Failed to activate swap /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b.
[    8.120639] Adding 16777212k swap on /dev/sda2.  Priority:-1 extents:1 across:16777212k FS
[    8.120661] systemd[1]: Unit dev-disk-by\x2duuid-da08bb2e\x2d69dc\x2d4a28\x2db994\x2d2f3183d2950b.swap entered failed state.

$ ~ journalctl -b | grep swap
Nov 12 08:26:26 edge systemd[1]: dev-disk-by\x2duuid-da08bb2e\x2d69dc\x2d4a28\x2db994\x2d2f3183d2950b.swap swap process exited, code=exited status=255
Nov 12 08:26:26 edge systemd[1]: Failed to activate swap /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b.
Nov 12 08:26:26 edge kernel: Adding 16777212k swap on /dev/sda2.  Priority:-1 extents:1 across:16777212k FS
Nov 12 08:26:26 edge systemd[1]: Unit dev-disk-by\x2duuid-da08bb2e\x2d69dc\x2d4a28\x2db994\x2d2f3183d2950b.swap entered failed state.
Nov 12 08:26:26 edge swapon[272]: swapon: /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b: swapon failed: Device or resource busy

$ ~ cat /etc/fstab | grep swap
# /dev/sda2 LABEL=swap
UUID=da08bb2e-69dc-4a28-b994-2f3183d2950b	none      	swap      	defaults  	0 0

$ ~ blkid | grep swap
/dev/sda2: LABEL="swap" UUID="da08bb2e-69dc-4a28-b994-2f3183d2950b" TYPE="swap" PARTLABEL="Linux swap" PARTUUID="02399d76-1160-42f3-898d-5306769965d3"

$ ~ cat /etc/default/grub
GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="Arch"
GRUB_CMDLINE_LINUX_DEFAULT="resume=/dev/disk/by-uuid/698e4f98-a2b5-4294-9b6d-a53aaf8bc64b quiet acpi_osi=Linux LOGLEVEL=2"
GRUB_CMDLINE_LINUX=""

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable Hidden Menu, and optionally hide the timeout count
#GRUB_HIDDEN_TIMEOUT=5
#GRUB_HIDDEN_TIMEOUT_QUIET=true

# Uncomment to use basic console
GRUB_TERMINAL_INPUT=console

# Uncomment to disable graphical terminal
#GRUB_TERMINAL_OUTPUT=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE=1920x1080x32

# Uncomment to allow the kernel use the same resolution used by grub
GRUB_GFXPAYLOAD_LINUX=keep

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
# GRUB_DISABLE_RECOVERY=true

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.
#GRUB_COLOR_NORMAL="light-blue/black"
#GRUB_COLOR_HIGHLIGHT="light-cyan/blue"

# Uncomment one of them for the gfx desired, a image background or a gfxtheme
#GRUB_BACKGROUND="/path/to/wallpaper"
#GRUB_THEME="/path/to/gfxtheme"
#GRUB_THEME="/boot/grub/themes/Archlinux/theme.txt"
GRUB_THEME="/boot/grub/themes/Archxion-widescreen/theme.txt"

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

#GRUB_SAVEDEFAULT="true"

$ ~ mount | grep swap
$ ~ # пусто

$ ~ sudo swapon /dev/sda2
[sudo] password for klay:
swapon: /dev/sda2: swapon failed: Device or resource busy

$ ~ swapon -s
Filename				Type		Size	Used	Priority
/dev/sda2                              	partition	16777212	0	-1

$ ~ free -h
             total       used       free     shared    buffers     cached
Mem:           15G       1.1G        14G        95M        34M       374M
-/+ buffers/cache:       761M        14G
Swap:          15G         0B        15G

$ ~ systemctl status dev-disk-by\\x2duuid-da08bb2e\\x2d69dc\\x2d4a28\\x2db994\\x2d2f3183d2950b.swap
● dev-disk-by\x2duuid-da08bb2e\x2d69dc\x2d4a28\x2db994\x2d2f3183d2950b.swap - /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b
   Loaded: loaded (/etc/fstab)
   Active: active (Result: exit-code) since Wed 2014-11-12 08:26:25 EET; 20min ago
     What: /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 272 ExecActivate=/sbin/swapon /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b (code=exited, status=255)

Nov 12 08:26:26 edge swapon[272]: swapon: /dev/disk/by-uuid/da08bb2e-69dc-4a28-b994-2f3183d2950b: swapon failed: Device or resource busy

$ ~ systemctl status dev-sda2.swap
● dev-sda2.swap - Swap Partition
   Loaded: loaded (/run/systemd/generator.late/dev-sda2.swap)
   Active: active since Wed 2014-11-12 08:26:25 EET; 2h 3min ago
     What: /dev/sda2
     Docs: man:systemd-gpt-auto-generator(8)
  Process: 271 ExecActivate=/sbin/swapon /dev/sda2 (code=exited, status=0/SUCCESS)