It is often critical to know exactly what is going on with your system.
Linux is the defacto winner of the server world in large part because there are so many good tools.
Especially since open source often needs to detect and reverse engineer drivers and compatibility for manufacturer hardware.
higher level utilities for process
ps
processes with their virtual memory size
top
processes and cpu usage, type q to quit
q = quit
s = change interval of refresh (default is 3 seconds)
u = type a User and only show processes from that User
> = choose to sort by the next column
< = choose to sort by the previous
ps -a
tree of all processes
ps -ef
full output of all processes including start time, uptime, cmd
ps -eo pid,ppid,rss,vsize,pcpu,pmem,cmd -ww --sort=pid
ps -eo pid,ppid,rss,vsize,pcpu,pmem,cmd -ww --sort=rss
rss = ram usage
vsize = virtual memory include swap as well
ps -eo rss,vsz,pid,cmd,cputime | sort -n | tail -20
(this will show you possible memory leaks)
ps guxca
so the free command is funny ( http://kbase.redhat.com/faq/docs/DOC-1139 )
the amount +/- buffers/cache is the "real" amount available to the system (if the "lazy" kernel decided to free up something that's been buffered previously in order for a new app which needs the memory)
<Physically Used Memory> = <Actual used memory> + <buffers> + <cache>
<Physically Free Memory> = <Total Physical Memory> - <Actual used memory> - <buffers> - <cache>
<Memory free for Applications> = <Total Physical Memory> - <Actual used memory>
<Memory used by Applications> = <Actual used memory> - <buffers> - <cache>
OS Version
cat /etc/issue
just the version number of the OS, e.g. ubuntu shows 16.04
cat /etc/debian_version
only on debian/ubuntu... and shows squeeze/sid for natty 11.04, wheezy/sid for 11.10, jessie/sid - https://www.debian.org/releases/
cat /etc/lsb-release
full ubuntu version
lsb_release -a
a command to shows all of the ubuntu version information, e.g. cat /etc/lsb-release
lsb_release -c
Codename: natty
a command to just show the codename
/proc is realtime info about the system
cat /proc/version
cat /proc/cpuinfo
note: if there's "lm" (aka long mode) in the flags: fpu vme etc. area then you have 64bit capability...
cat /proc/meminfo
head -1 /proc/meminfo
ls -ld /proc/somepid
get some info about a specific process running via its pid number
kernel information
uname -a
kernel version, x64 or 32 bit, machine name , multi-processor SMP, etc.
getconf -a
another way to get info about your kernel
Memory and disk space
free -m
free memory in megabytes including swap/buffer usage)
vmstat
/virtual memory stats
df -h
free disk space in human readable numbers
du
disk usage for a directory and subdirectories - needs parameters , like
du -sh(summary with human readable sizes)
du -a . | sort -nr | head -n 10
disk usage for all files in the current directory and subdirectories reverse sorted for largest 10 items
-
https://linux.die.net/man/1/du
stat -f / -c "%a * %s / 1024" | bc
get the specific amount of free space available from the root file system, stat --help bc is a handy "built in calculator"
hardware listing
fdisk -l
shows all of the hard disk devices available - what os, bootable, etc.
lshw
exhaustive info about the hardware (tree by CLASS)
lshw -class network
hardware listing focused identification of Physical Network Adapter to logical name like eth0/wlan0
lshw -c video
show the video hardware
lspci
lists devices connected to the PCI bus requires pciutils.deb depends on libpci3 , all the pci hardware including usb bridges,agp cards common usages are "lspci | grep vga" or "lspci | grep eth"
lsusb
will show all the usb devices like mice, etc
dmidecode
listing of system hardware according to the BIOS (so not always reliable) http://www.nongnu.org/dmidecode/
lsmod
installed driver modules
xdpyinfo
/xserver info
ls -l /lib/libc-*.so /lib/libc.so*
ldd --version
version of linux glibc
dmesg
kernel messages = all the devices the kernel has found like hard disks,cdroms,etc
dmesg | grep CPU
dmesg | grep mem
dmesg | tail
shows the last 10 lines of the hardware boot up
/etc/modprobe.conf (kernel 2.6)
fedora/redhat /etc/modules.conf (kernel 2.4)
/etc/conf.modules (or for older systems)
disk IO
iotop
like top but focused on I/O , http://linux.die.net/man/1/iotop
network
ifconfig -a
shows all of the ethernet devices available
ls -l /sys/class/net/eth0
apt-get install bcm43xx-fwcutter
mkdir -p /lib/hotplug/firmware; cp /lib/firmware/*.fw /lib/hotplug/firmware
software inventory and listing
dpkg --list
dpkg -l | grep foo
dpkg --get-selections
debian/ubuntu listing of installed software packages
pip freeze
pip freeze | grep foo
python packaging manager listing of packages
rpm -qa
red hat installed software
tail -f /var/log/secure //login logs
tail -f /var/log/maillog //mail logs
last
last -f btmp
last logins and then the last bad logins
cat /proc/meminfo
MemTotal = Total amount of physical RAM, in kilobytes. MemFree The amount of physical RAM, in kilobytes, left unused by the system.
note that MemTotal - MemFree should match what free and top show you...
Slab The total amount of memory, in kilobytes, used by the kernel to cache data structures for its own use.
Mapped The total amount of memory, in kilobytes, which have been used to map devices, files, or libraries using the mmap command.
So all of your processes from TOP + Slab + Mapped
free
total used free shared buffers cached
Mem: 262364 78424 183940 0 2412 37756
-/+ buffers/cache: 38256 224108
Swap: 524280 0 524280
used + buffer + cached = 118,592
143,772
top - 20:39:34 up 2:19, 1 user, load average: 0.00, 0.00, 0.00
Tasks: 55 total, 1 running, 54 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.8%st
Mem: 262364k total, 78408k used, 183956k free, 2428k buffers
Swap: 524280k total, 0k used, 524280k free, 37756k cached
3899 root 20 0 68112 2984 2316 S 0 1.1 0:00.42 sshd
3575 klog 20 0 5492 2260 420 S 0 0.9 0:00.06 klogd
3903 root 20 0 17544 1796 1328 S 0 0.7 0:00.16 bash
4490 root 20 0 18860 1200 932 R 0 0.5 0:00.04 top
3596 root 20 0 50916 1164 680 S 0 0.4 0:00.00 sshd
3856 Debian-e 20 0 43432 1000 616 S 0 0.4 0:00.00 exim4
1 root 20 0 4020 944 656 S 0 0.4 0:00.36 init
2300 root 16 -4 16832 932 372 S 0 0.4 0:00.46 udevd
3874 root 20 0 18616 860 668 S 0 0.3 0:00.04 cron
3550 syslog 20 0 12296 752 564 S 0 0.3 0:00.10 syslogd
3510 root 20 0 3864 588 492 S 0 0.2 0:00.00 getty
3513 root 20 0 3864 588 492 S 0 0.2 0:00.00 getty
3516 root 20 0 3864 588 492 S 0 0.2 0:00.00 getty
3572 root 20 0 8132 588 476 S 0 0.2 0:00.04 dd
3509 root 20 0 3864 584 492 S 0 0.2 0:00.00 getty
3512 root 20 0 3864 584 492 S 0 0.2 0:00.00 getty
3898 root 20 0 3864 584 492 S 0 0.2 0:00.00 getty
17,996 + 15,832 + 3,552 = 37,380... so still short of 78,424
TOP + Slab + Mapped
http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/
http://backtrack.offensive-security.com/index.php/HCL:Wireless#Linksys_WPC54G_v3
Linksys WPC54G v3
* Driver : bcm43xx/b43
* Chipset : Broadcom Corporation BCM4318 [AirForce One 54g] 802.11g Wireless LAN Controller (rev 02)
* Subsystem: Linksys WPC54G-EU version 3 [Wireless-G Notebook Adapter]
Monitor mode currently supported but injection may or may not work with bcm43xx. Apparently a new driver is coming out dubbed as b43 and is only available in either kernel >=2.6.24 and/or wireless-2.6 git. Injection will work after patching b43 via mac80211 stack. bcm43xx driver will soon be deprecated and for this chipset it will not indicate PWR levels with airodump-ng.
http://linuxwireless.org/en/users/Drivers/b43
lspci -vnn | grep 14e4
0001:01:01.0 Network controller [0280]: Broadcom Corporation BCM4318 [AirForce One 54g] 802.11g Wireless LAN Controller [14e4:4318] (rev 02)
cat /proc/interrupts
a file listing of all the interrupt IRQs used by your system
e.g.
CPU0
0: 2707402473 XT-PIC timer
1: 67 XT-PIC i8042
2: 0 XT-PIC cascade
5: 411342 XT-PIC eth1
8: 1 XT-PIC rtc
10: 1898752 XT-PIC eth0
11: 0 XT-PIC uhci_hcd
12: 58 XT-PIC i8042
14: 5075806 XT-PIC ide0
15: 506 XT-PIC ide1
NMI: 0
ERR: 43
if two devices try to use the same interrupts or memory access address they will be in conflict (won't work)
dmidecode in depth example
DMI DECODE for how much physical ram you COULD have...
dmidecode > hw.txt
dump the whole thing to a text file
less hw.txt
lots of info!
System Information
Manufacturer: HP
Product Name: ProLiant ML310 G5
Version: Not Specified
Serial Number:
UUID:
Wake-up Type: Power Switch
SKU Number:
Family: ProLiant
Processor Information
Socket Designation: Proc 1
Type: Central Processor
Family: Xeon
Manufacturer: Intel
ID: 77 06 01 00 FF FB EB BF
Signature: Type 0, Family 6, Model 23, Stepping 7
External Clock: 1333 MHz
Max Speed: 4800 MHz
Current Speed: 2500 MHz
Status: Populated, Enabled
Upgrade: ZIF Socket
L1 Cache Handle: 0x0710
L2 Cache Handle: 0x0720
L3 Cache Handle: 0x0730
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Core Count: 4
Core Enabled: 4
Thread Count: 4
Characteristics:
64-bit capable
BECAUSE THERE IS SO MUCH INFORMATION PEOPLE USE TRICKS TO GET ONLY A CERTAIN PART
dmidecode | perl -ne '$memory += $1 if /^\t+Size: (\d+)/ ; END { print "$memory\n" }'
dmidecode | perl -ne '$num_procs += 1 if /^\t+Type: Central Processor/ ; END { print "$num_procs\n"}'
decode, biosdecode, and vpddecode //alternates to dmidecode?
DMI SHORT CODES MAKE IT EASIER TO GET A SPECIFIC CHUNK
dmidecode --type 0
get info on the bios
dmidecode --type 16
# dmidecode 2.9
SMBIOS 2.4 present.
Handle 0x1000, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Single-bit ECC
Maximum Capacity: 8 GB
Error Information Handle: Not Provided
Number Of Devices: 4
# Type Short Description
0 BIOS
1 System
2 Base Board
3 Chassis
4 Processor
5 Memory Controller
6 Memory Module
7 Cache
8 Port Connector
9 System Slots
10 On Board Devices
11 OEM Strings
12 System Configuration Options
13 BIOS Language
14 Group Associations
15 System Event Log
16 Physical Memory Array
17 Memory Device
18 32-bit Memory Error
19 Memory Array Mapped Address
20 Memory Device Mapped Address
21 Built-in Pointing Device
22 Portable Battery
23 System Reset
24 Hardware Security
25 System Power Controls
26 Voltage Probe
27 Cooling Device
28 Temperature Probe
29 Electrical Current Probe
30 Out-of-band Remote Access
31 Boot Integrity Services
32 System Boot
33 64-bit Memory Error
34 Management Device
35 Management Device Component
36 Management Device Threshold Data
37 Memory Channel
38 IPMI Device
39 Power Supply