Tag Archives: linux

just a bunch of useful linux tools/commands to remember

Useful HD slice info:
tune2fs -l /dev/xx
Sort it out:
mount -l -t ext3 | cut -d' ' -f1 | xargs -n1 tune2fs -l | egrep -i 'state|mount|check'
Reboot without fsck:
shutdown -ir now

stat – useful file info
strip – remove ‘some junk’ from compiled programm

htop
mtop – MySQL terminal based query monitor
dstat – versatile resource statistics tool

blkid – command-line utility to locate/print block device attributes (shows UUID of device)
dumpe2fs – dump ext2/ext3 filesystem information
nc – TCP/IP swiss army knife
————————————

Command Description
apropos whatis Show commands pertinent to string. See also threadsafe
man -t ascii | ps2pdf – > ascii.pdf make a pdf of a manual page
  which command Show full path name of command
  time command See how long a command takes
time cat Start stopwatch. Ctrl-d to stop. See also sw
dir navigation
cd – Go to previous directory
cd Go to $HOME directory
  (cd dir && command) Go to dir, execute command and return to current dir
pushd . Put current dir on stack so you can popd back to it
alias l=’ls -l –color=auto’ quick dir listing
ls -lrt List files by date. See also newest and find_mm_yyyy
ls /usr/bin | pr -T9 -W$COLUMNS Print in 9 columns to width of terminal
  find -name ‘*.[ch]’ | xargs grep -E ‘expr’ Search ‘expr’ in this dir and below. See also findrepo
  find -type f -print0 | xargs -r0 grep -F ‘example’ Search all regular files for ‘example’ in this dir and below
  find -maxdepth 1 -type f | xargs grep -F ‘example’ Search all regular files for ‘example’ in this dir
  find -maxdepth 1 -type d | while read dir; do echo $dir; echo cmd2; done Process each item with multiple commands (in while loop)
find -type f ! -perm -444 Find files not readable by all (useful for web site)
find -type d ! -perm -111 Find dirs not accessible by all (useful for web site)
locate -r ‘file[^/]*.txt’ Search cached index for names. This re is like glob *file*.txt
look reference Quickly search (sorted) dictionary for prefix
grep –color reference /usr/share/dict/words Highlight occurances of regular expression in dictionary
archives and compression
  gpg -c file Encrypt file
  gpg file.gpg Decrypt file
  tar -c dir/ | bzip2 > dir.tar.bz2 Make compressed archive of dir/
  bzip2 -dc dir.tar.bz2 | tar -x Extract archive (use gzip instead of bzip2 for tar.gz files)
  tar -c dir/ | gzip | gpg -c | ssh user@remote ‘dd of=dir.tar.gz.gpg’ Make encrypted archive of dir/ on remote machine
  find dir/ -name ‘*.txt’ | tar -c –files-from=- | bzip2 > dir_txt.tar.bz2 Make archive of subset of dir/ and below
  find dir/ -name ‘*.txt’ | xargs cp -a –target-directory=dir_txt/ –parents Make copy of subset of dir/ and below
  ( tar -c /dir/to/copy ) | ( cd /where/to/ && tar -x -p ) Copy (with permissions) copy/ dir to /where/to/ dir
  ( cd /dir/to/copy && tar -c . ) | ( cd /where/to/ && tar -x -p ) Copy (with permissions) contents of copy/ dir to /where/to/
  ( tar -c /dir/to/copy ) | ssh -C user@remote ‘cd /where/to/ && tar -x -p’ Copy (with permissions) copy/ dir to remote:/where/to/ dir
  dd bs=1M if=/dev/sda | gzip | ssh user@remote ‘dd of=sda.gz’ Backup harddisk to remote machine
rsync (Network efficient file copier: Use the –dry-run option for testing)
  rsync -P rsync://rsync.server.com/path/to/file file Only get diffs. Do multiple times for troublesome downloads
  rsync –bwlimit=1000 fromfile tofile Locally copy with rate limit. It’s like nice for I/O
  rsync -az -e ssh –delete ~/public_html/ remote.com:’~/public_html’ Mirror web site (using compression and encryption)
  rsync -auz -e ssh remote:/dir/ . && rsync -auz -e ssh . remote:/dir/ Synchronize current directory with remote one
ssh (Secure SHell)
  ssh $USER@$HOST command Run command on $HOST as $USER (default command=shell)
ssh -f -Y $USER@$HOSTNAME xeyes Run GUI command on $HOSTNAME as $USER
  scp -p -r $USER@$HOST: file dir/ Copy with permissions to $USER’s home directory on $HOST
  scp -c arcfour $USER@$LANHOST: bigfile Use faster crypto for local LAN. This might saturate GigE
  ssh -g -L 8080:localhost:80 root@$HOST Forward connections to $HOSTNAME:8080 out to $HOST:80
  ssh -R 1434:imap:143 root@$HOST Forward connections from $HOST:1434 in to imap:143
  ssh-copy-id $USER@$HOST Install public key for $USER@$HOST for password-less log in
wget (multi purpose download tool)
(cd dir/ && wget -nd -pHEKk http://www.pixelbeat.org/cmdline.html) Store local browsable version of a page to the current dir
  wget -c http://www.example.com/large.file Continue downloading a partially downloaded file
  wget -r -nd -np -l1 -A ‘*.jpg’ http://www.example.com/dir/ Download a set of files to the current directory
  wget ftp://remote/file[1-9].iso/ FTP supports globbing directly
wget -q -O- http://www.pixelbeat.org/timeline.html | grep ‘a href’ | head Process output directly
  echo ‘wget url’ | at 01:00 Download url at 1AM to current dir
  wget –limit-rate=20k url Do a low priority download (limit to 20KB/s in this case)
  wget -nv –spider –force-html -i bookmarks.html Check links in a file
  wget –mirror http://www.example.com/ Efficiently update a local copy of a site (handy from cron)
networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete)
  ethtool eth0 Show status of ethernet interface eth0
  ethtool –change eth0 autoneg off speed 100 duplex full Manually set ethernet interface speed
  iwconfig eth1 Show status of wireless interface eth1
  iwconfig eth1 rate 1Mb/s fixed Manually set wireless interface speed
iwlist scan List wireless networks in range
ip link show List network interfaces
  ip link set dev eth0 name wan Rename interface eth0 to wan
  ip link set dev eth0 up Bring interface eth0 up (or down)
ip addr show List addresses for interfaces
  ip addr add 1.2.3.4/24 brd + dev eth0 Add (or del) ip and mask (255.255.255.0)
ip route show List routing table
  ip route add default via 1.2.3.254 Set default gateway to 1.2.3.254
host pixelbeat.org Lookup DNS ip address for name or vice versa
hostname -i Lookup local ip address (equivalent to host `hostname`)
whois pixelbeat.org Lookup whois info for hostname or ip address
netstat -tupl List internet services on a system
netstat -tup List active connections to/from system
windows networking (Note samba is the package that provides all this windows specific networking support)
smbtree Find windows machines. See also findsmb
  nmblookup -A 1.2.3.4 Find the windows (netbios) name associated with ip address
  smbclient -L windows_box List shares on windows machine or samba server
  mount -t smbfs -o fmask=666,guest //windows_box/share /mnt/share Mount a windows share
  echo ‘message’ | smbclient -M windows_box Send popup to windows machine (off by default in XP sp2)
text manipulation (Note sed uses stdin and stdout. Newer versions support inplace editing with the -i option)
  sed ‘s/string1/string2/g’ Replace string1 with string2
  sed ‘s/(.*)1/12/g’ Modify anystring1 to anystring2
  sed ‘/ *#/d; /^ *$/d’ Remove comments and blank lines
  sed ‘:a; /\$/N; s/\n//; ta’ Concatenate lines with trailing
  sed ‘s/[ t]*$//’ Remove trailing spaces from lines
  sed ‘s/([`"$])/\1/g’ Escape shell metacharacters active within double quotes
seq 10 | sed “s/^/      /; s/ *(.{7,})/1/” Right align numbers
  sed -n ‘1000{p;q}’ Print 1000th line
  sed -n ‘10,20p;20q Print lines 10 to 20
  sed -n ‘s/.*<title>(.*)</title>.*/1/ip;T;q Extract title from HTML web page
  sed -i 42d ~/.ssh/known_hosts Delete a particular line
  sort -t. -k1,1n -k2,2n -k3,3n -k4,4n Sort IPV4 ip addresses
echo ‘Test’ | tr ‘[:lower:]’ ‘[:upper:]’ Case conversion
tr -dc ‘[:print:]’ < /dev/urandom Filter non printable characters
tr -s ‘[:blank:]’ ‘t’ </proc/diskstats | cut -f4 cut fields separated by blanks
history | wc -l Count lines
set operations (Note you can export LANG=C for speed. Also these assume no duplicate lines within a file)
  sort file1 file2 | uniq Union of unsorted files
  sort file1 file2 | uniq -d Intersection of unsorted files
  sort file1 file1 file2 | uniq -u Difference of unsorted files
  sort file1 file2 | uniq -u Symmetric Difference of unsorted files
  join -t’�’ -a1 -a2 file1 file2 Union of sorted files
  join -t’�’ file1 file2 Intersection of sorted files
  join -t’�’ -v2 file1 file2 Difference of sorted files
  join -t’�’ -v1 -v2 file1 file2 Symmetric Difference of sorted files
math
echo ‘(1 + sqrt(5))/2’ | bc -l Quick math (Calculate φ). See also bc
seq -f ‘4/%g’ 1 2 99999 | paste -sd-+ | bc -l Calculate π the unix way
echo ‘pad=20; min=64; (100*10^6)/((pad+min)*8)’ | bc More complex (int) e.g. This shows max FastE packet rate
echo ‘pad=20; min=64; print (100E6)/((pad+min)*8)’ | python Python handles scientific notation
echo ‘pad=20; plot [64:1518] (100*10**6)/((pad+x)*8)’ | gnuplot -persist Plot FastE packet rate vs packet size
echo ‘obase=16; ibase=10; 64206’ | bc Base conversion (decimal to hexadecimal)
echo $((0x2dec)) Base conversion (hex to dec) ((shell arithmetic expansion))
units -t ‘100m/9.58s‘ ‘miles/hour’ Unit conversion (metric to imperial)
units -t ‘500GB’ ‘GiB’ Unit conversion (SI to IEC prefixes)
units -t ‘1 googol’ Definition lookup
seq 100 | (tr ‘n’ +; echo 0) | bc Add a column of numbers. See also add and funcpy
calendar
cal -3 Display a calendar
cal 9 1752 Display a calendar for a particular month year
date -d fri What date is it this friday. See also day
[ $(date -d “tomorrow” +%d) = “01” ] || exit exit a script unless it’s the last day of the month
date –date=’25 Dec’ +%A What day does xmas fall on, this year
date –date=’@2147483647′ Convert seconds since the epoch (1970-01-01 UTC) to date
TZ=’America/Los_Angeles’ date What time is it on west coast of US (use tzselect to find TZ)
date –date=’TZ=”America/Los_Angeles” 09:00 next Fri’ What’s the local time for 9AM next Friday on west coast US
locales
printf "%’dn" 1234 Print number with thousands grouping appropriate to locale
BLOCK_SIZE=’1 ls -l Use locale thousands grouping in ls. See also l
echo "I live in `locale territory`" Extract info from locale database
LANG=en_IE.utf8 locale int_prefix Lookup locale info for specific country. See also ccodes
locale -kc $(locale | sed -n ‘s/(LC_.{4,})=.*/1/p’) | less List fields available in locale database
recode (Obsoletes iconv, dos2unix, unix2dos)
recode -l | less Show available conversions (aliases on each line)
  recode windows-1252.. file_to_change.txt Windows “ansi” to local charset (auto does CRLF conversion)
  recode utf-8/CRLF.. file_to_change.txt Windows utf8 to local charset
  recode iso-8859-15..utf8 file_to_change.txt Latin9 (western europe) to utf8
  recode ../b64 < file.txt > file.b64 Base64 encode
  recode /qp.. < file.qp > file.txt Quoted printable decode
  recode ..HTML < file.txt > file.html Text to HTML
recode -lf windows-1252 | grep euro Lookup table of characters
echo -n 0x80 | recode latin-9/x1..dump Show what a code represents in latin-9 charmap
echo -n 0x20AC | recode ucs-2/x2..latin-9/x Show latin-9 encoding
echo -n 0x20AC | recode ucs-2/x2..utf-8/x Show utf-8 encoding
CDs
  gzip < /dev/cdrom > cdrom.iso.gz Save copy of data cdrom
  mkisofs -V LABEL -r dir | gzip > cdrom.iso.gz Create cdrom image from contents of dir
  mount -o loop cdrom.iso /mnt/dir Mount the cdrom image at /mnt/dir (read only)
  cdrecord -v dev=/dev/cdrom blank=fast Clear a CDRW
  gzip -dc cdrom.iso.gz | cdrecord -v dev=/dev/cdrom – Burn cdrom image (use dev=ATAPI -scanbus to confirm dev)
  cdparanoia -B Rip audio tracks from CD to wav files in current dir
  cdrecord -v dev=/dev/cdrom -audio -pad *.wav Make audio CD from all wavs in current dir (see also cdrdao)
  oggenc –tracknum=’track’ track.cdda.wav -o ‘track.ogg’ Make ogg file from wav file
disk space (See also FSlint)
ls -lSr Show files by size, biggest last
du -s * | sort -k1,1rn | head Show top disk users in current dir. See also dutop
du -hs /home/* | sort -k1,1h Sort paths by easy to interpret disk usage
df -h Show free space on mounted filesystems
df -i Show free inodes on mounted filesystems
fdisk -l Show disks partitions sizes and types (run as root)
rpm -q -a –qf ‘%10{SIZE}t%{NAME}n’ | sort -k1,1n List all packages by installed size (Bytes) on rpm distros
dpkg-query -W -f=’${Installed-Size;10}t${Package}n’ | sort -k1,1n List all packages by installed size (KBytes) on deb distros
dd bs=1 seek=2TB if=/dev/null of=ext3.test Create a large test file (taking no space). See also truncate
> file truncate data of file or create an empty file
monitoring/debugging
tail -f /var/log/messages Monitor messages in a log file
strace -c ls >/dev/null Summarise/profile system calls made by command
strace -f -e open ls >/dev/null List system calls made by command
strace -f -e trace=write -e write=1,2 ls >/dev/null Monitor what’s written to stdout and stderr
ltrace -f -e getenv ls >/dev/null List library calls made by command
lsof -p $$ List paths that process id has open
lsof ~ List processes that have specified path open
tcpdump not port 22 Show network traffic except ssh. See also tcpdump_not_me
ps -e -o pid,args –forest List processes in a hierarchy
ps -e -o pcpu,cpu,nice,state,cputime,args –sort pcpu | sed ‘/^ 0.0 /d’ List processes by % cpu usage
ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS List processes by mem (KB) usage. See also ps_mem.py
ps -C firefox-bin -L -o pid,tid,pcpu,state List all threads for a particular process
ps -p 1,$$ -o etime= List elapsed wall time for particular process IDs
last reboot Show system reboot history
free -m Show amount of (remaining) RAM (-m displays in MB)
watch -n.1 ‘cat /proc/interrupts’ Watch changeable data continuously
udevadm monitor Monitor udev events to help configure rules
system information (see also sysinfo) (‘#’ means root access is required)
uname -a Show kernel version and system architecture
head -n1 /etc/issue Show name and version of distribution
cat /proc/partitions Show all partitions registered on the system
grep MemTotal /proc/meminfo Show RAM total seen by the system
grep “model name” /proc/cpuinfo Show CPU(s) info
lspci -tv Show PCI info
lsusb -tv Show USB info
mount | column -t List mounted filesystems on the system (and align output)
grep -F capacity: /proc/acpi/battery/BAT0/info Show state of cells in laptop battery
# dmidecode -q | less Display SMBIOS/DMI information
# smartctl -A /dev/sda | grep Power_On_Hours How long has this disk (system) been powered on in total
# hdparm -i /dev/sda Show info about disk sda
# hdparm -tT /dev/sda Do a read speed test on disk sda
# badblocks -s /dev/sda Test for unreadable blocks on disk sda
interactive (see also linux keyboard shortcuts)
readline Line editor used by bash, python, bc, gnuplot, …
screen Virtual terminals with detach capability, …
mc Powerful file manager that can browse rpm, tar, ftp, ssh, …
gnuplot Interactive/scriptable graphing
links Web browser
xdg-open . open a file or url with the registered desktop application

(c) http://www.pixelbeat.org/cmdline.html

tar system backup&restore

Backup:

tar cvpzf backup.tgz --exclude=/proc --exclude=/lost+found --exclude=/backup.tgz --exclude=/mnt --exclude=/sys /

or

tar cvpjf backup.tar.bz2 --exclude=/proc --exclude=/lost+found --exclude=/backup.tar.bz2 --exclude=/mnt --exclude=/sys /

Restore:

tar xvpfz backup.tgz -C /

tar xvpfj backup.tar.bz2 -C /

+
mkdir proc
mkdir lost+found
mkdir mnt
mkdir sys

Tar Over SSH

tar -cpzf - ./ | ssh remoteuser@remotehost tar -C /path/to/remote/dir -xpzf -
tar -cpzf - ./ | ssh remoteuser@remotehost "cat > /path/backup.tgz"
ssh remoteuser@remotehost "tar -cpzf - --exclude=/proc --exclude=/lost+found --exclude=/mnt --exclude=/sys /" | tar -C /path -xpzf -

http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

#1: top – Process Activity Command

The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

Fig.01: Linux top commandFig.01: Linux top command

Commonly Used Hot Keys

The top command provides several useful hot keys:

Hot Key Usage
t Displays summary information off and on.
m Displays memory information off and on.
A Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o Enables you to interactively select the ordering within top.
r Issues renice command.
k Issues kill command.
z Turn on or off color/mono

=> Related: How do I Find Out Linux CPU Utilization?

#2: vmstat – System Activity, Hardware and System Information

The command vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.
# vmstat 3
Sample Outputs:

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 2540988 522188 5130400    0    0     2    32    4    2  4  1 96  0  0
 1  0      0 2540988 522188 5130400    0    0     0   720 1199  665  1  0 99  0  0
 0  0      0 2540956 522188 5130400    0    0     0     0 1151 1569  4  1 95  0  0
 0  0      0 2540956 522188 5130500    0    0     0     6 1117  439  1  0 99  0  0
 0  0      0 2540940 522188 5130512    0    0     0   536 1189  932  1  0 98  0  0
 0  0      0 2538444 522188 5130588    0    0     0     0 1187 1417  4  1 96  0  0
 0  0      0 2490060 522188 5130640    0    0     0    18 1253 1123  5  1 94  0  0

Display Memory Utilization Slabinfo

# vmstat -m

Get Information About Active / Inactive Memory Pages

# vmstat -a
=> Related: How do I find out Linux Resource utilization to detect system bottlenecks?

#3: w – Find Out Who Is Logged on And What They Are Doing

w command displays information about the users currently on the machine, and their processes.
# w username
# w vivek

Sample Outputs:

 17:58:47 up 5 days, 20:28,  2 users,  load average: 0.36, 0.26, 0.24
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
root     pts/0    10.1.3.145       14:55    5.00s  0.04s  0.02s vim /etc/resolv.conf
root     pts/1    10.1.3.145       17:43    0.00s  0.03s  0.00s w

#4: uptime – Tell How Long The System Has Been Running

The uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.
# uptime
Output:

 18:02:41 up 41 days, 23:42,  1 user,  load average: 0.00, 0.00, 0.00

1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 – 3 and SMP systems 6-10 load value might be acceptable.

#5: ps – Displays The Processes

ps command will report a snapshot of the current processes. To select all processes use the -A or -e option:
# ps -A
Sample Outputs:

  PID TTY          TIME CMD
    1 ?        00:00:02 init
    2 ?        00:00:02 migration/0
    3 ?        00:00:01 ksoftirqd/0
    4 ?        00:00:00 watchdog/0
    5 ?        00:00:00 migration/1
    6 ?        00:00:15 ksoftirqd/1
....
.....
 4881 ?        00:53:28 java
 4885 tty1     00:00:00 mingetty
 4886 tty2     00:00:00 mingetty
 4887 tty3     00:00:00 mingetty
 4888 tty4     00:00:00 mingetty
 4891 tty5     00:00:00 mingetty
 4892 tty6     00:00:00 mingetty
 4893 ttyS1    00:00:00 agetty
12853 ?        00:00:00 cifsoplockd
12854 ?        00:00:00 cifsdnotifyd
14231 ?        00:10:34 lighttpd
14232 ?        00:00:00 php-cgi
54981 pts/0    00:00:00 vim
55465 ?        00:00:00 php-cgi
55546 ?        00:00:00 bind9-snmp-stat
55704 pts/1    00:00:00 ps

ps is just like top but provides more information.

Show Long Format Output

# ps -Al
To turn on extra full mode (it will show command line arguments passed to process):
# ps -AlF

To See Threads ( LWP and NLWP)

# ps -AlFH

To See Threads After Processes

# ps -AlLm

Print All Process On The Server

# ps ax
# ps axu

Print A Process Tree

# ps -ejH
# ps axjf
# pstree

Print Security Information

# ps -eo euser,ruser,suser,fuser,f,comm,label
# ps axZ
# ps -eM

See Every Process Running As User Vivek

# ps -U vivek -u vivek u

Set Output In a User-Defined Format

# ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
# ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm
# ps -eopid,tt,user,fname,tmout,f,wchan

Display Only The Process IDs of Lighttpd

# ps -C lighttpd -o pid=
OR
# pgrep lighttpd
OR
# pgrep -u vivek php-cgi

Display The Name of PID 55977

# ps -p 55977 -o comm=

Find Out The Top 10 Memory Consuming Process

# ps -auxf | sort -nr -k 4 | head -10

Find Out top 10 CPU Consuming Process

# ps -auxf | sort -nr -k 3 | head -10

#6: free – Memory Usage

The command free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel.
# free
Sample Output:

            total       used       free     shared    buffers     cached
Mem:      12302896    9739664    2563232          0     523124    5154740
-/+ buffers/cache:    4061800    8241096
Swap:      1052248          0    1052248

=> Related: :

  1. Linux Find Out Virtual Memory PAGESIZE
  2. Linux Limit CPU Usage Per Process
  3. How much RAM does my Ubuntu / Fedora Linux desktop PC have?

#7: iostat – Average CPU Load, Disk Activity

The command iostat report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitions and network filesystems (NFS).
# iostat
Sample Outputs:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 	06/26/2009

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           3.50    0.09    0.51    0.03    0.00   95.86

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              22.04        31.88       512.03   16193351  260102868
sda1              0.00         0.00         0.00       2166        180
sda2             22.04        31.87       512.03   16189010  260102688
sda3              0.00         0.00         0.00       1615          0

=> Related: : Linux Track NFS Directory / Disk I/O Stats

#8: sar – Collect and Report System Activity

The sar command is used to collect, report, and save system activity information. To see network counter, enter:
# sar -n DEV | more
To display the network counters from the 24th:
# sar -n DEV -f /var/log/sa/sa24 | more
You can also display real time usage using sar:
# sar 4 5
Sample Outputs:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 		06/26/2009

06:45:12 PM       CPU     %user     %nice   %system   %iowait    %steal     %idle
06:45:16 PM       all      2.00      0.00      0.22      0.00      0.00     97.78
06:45:20 PM       all      2.07      0.00      0.38      0.03      0.00     97.52
06:45:24 PM       all      0.94      0.00      0.28      0.00      0.00     98.78
06:45:28 PM       all      1.56      0.00      0.22      0.00      0.00     98.22
06:45:32 PM       all      3.53      0.00      0.25      0.03      0.00     96.19
Average:          all      2.02      0.00      0.27      0.01      0.00     97.70

=> Related: : How to collect Linux system utilization data into a file

#9: mpstat – Multiprocessor Usage

The mpstat command displays activities for each available processor, processor 0 being the first one. mpstat -P ALL to display average CPU utilization per processor:
# mpstat -P ALL
Sample Output:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in)	 	06/26/2009

06:48:11 PM  CPU   %user   %nice    %sys %iowait    %irq   %soft  %steal   %idle    intr/s
06:48:11 PM  all    3.50    0.09    0.34    0.03    0.01    0.17    0.00   95.86   1218.04
06:48:11 PM    0    3.44    0.08    0.31    0.02    0.00    0.12    0.00   96.04   1000.31
06:48:11 PM    1    3.10    0.08    0.32    0.09    0.02    0.11    0.00   96.28     34.93
06:48:11 PM    2    4.16    0.11    0.36    0.02    0.00    0.11    0.00   95.25      0.00
06:48:11 PM    3    3.77    0.11    0.38    0.03    0.01    0.24    0.00   95.46     44.80
06:48:11 PM    4    2.96    0.07    0.29    0.04    0.02    0.10    0.00   96.52     25.91
06:48:11 PM    5    3.26    0.08    0.28    0.03    0.01    0.10    0.00   96.23     14.98
06:48:11 PM    6    4.00    0.10    0.34    0.01    0.00    0.13    0.00   95.42      3.75
06:48:11 PM    7    3.30    0.11    0.39    0.03    0.01    0.46    0.00   95.69     76.89

=> Related: : Linux display each multiple SMP CPU processors utilization individually.

#10: pmap – Process Memory Usage

The command pmap report memory map of a process. Use this command to find out causes of memory bottlenecks.
# pmap -d PID
To display process memory information for pid # 47394, enter:
# pmap -d 47394
Sample Outputs:

47394:   /usr/bin/php-cgi
Address           Kbytes Mode  Offset           Device    Mapping
0000000000400000    2584 r-x-- 0000000000000000 008:00002 php-cgi
0000000000886000     140 rw--- 0000000000286000 008:00002 php-cgi
00000000008a9000      52 rw--- 00000000008a9000 000:00000   [ anon ]
0000000000aa8000      76 rw--- 00000000002a8000 008:00002 php-cgi
000000000f678000    1980 rw--- 000000000f678000 000:00000   [ anon ]
000000314a600000     112 r-x-- 0000000000000000 008:00002 ld-2.5.so
000000314a81b000       4 r---- 000000000001b000 008:00002 ld-2.5.so
000000314a81c000       4 rw--- 000000000001c000 008:00002 ld-2.5.so
000000314aa00000    1328 r-x-- 0000000000000000 008:00002 libc-2.5.so
000000314ab4c000    2048 ----- 000000000014c000 008:00002 libc-2.5.so
.....
......
..
00002af8d48fd000       4 rw--- 0000000000006000 008:00002 xsl.so
00002af8d490c000      40 r-x-- 0000000000000000 008:00002 libnss_files-2.5.so
00002af8d4916000    2044 ----- 000000000000a000 008:00002 libnss_files-2.5.so
00002af8d4b15000       4 r---- 0000000000009000 008:00002 libnss_files-2.5.so
00002af8d4b16000       4 rw--- 000000000000a000 008:00002 libnss_files-2.5.so
00002af8d4b17000  768000 rw-s- 0000000000000000 000:00009 zero (deleted)
00007fffc95fe000      84 rw--- 00007ffffffea000 000:00000   [ stack ]
ffffffffff600000    8192 ----- 0000000000000000 000:00000   [ anon ]
mapped: 933712K    writeable/private: 4304K    shared: 768000K

The last line is very important:

  • mapped: 933712K total amount of memory mapped to files
  • writeable/private: 4304K the amount of private address space
  • shared: 768000K the amount of address space this process is sharing with others

=> Related: : Linux find the memory used by a program / process using pmap command

#11 and #12: netstat and ss – Network Statistics

The command netstat displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. ss command is used to dump socket statistics. It allows showing information similar to netstat. See the following resources about ss and netstat commands:

#13: iptraf – Real-time Network Statistics

The iptraf command is interactive colorful IP LAN monitor. It is an ncurses-based IP LAN monitor that generates various network statistics including TCP info, UDP counts, ICMP and OSPF information, Ethernet load info, node stats, IP checksum errors, and others. It can provide the following info in easy to read format:

  • Network traffic statistics by TCP connection
  • IP traffic statistics by network interface
  • Network traffic statistics by protocol
  • Network traffic statistics by TCP/UDP port and by packet size
  • Network traffic statistics by Layer2 address
Fig.02: General interface statistics: IP traffic statistics by network interface Fig.02: General interface statistics: IP traffic statistics by network interface

Fig.03 Network traffic statistics by TCP connectionFig.03 Network traffic statistics by TCP connection

#14: tcpdump – Detailed Network Traffic Analysis

The tcpdump is simple command that dump traffic on a network. However, you need good understanding of TCP/IP protocol to utilize this tool. For.e.g to display traffic info about DNS, enter:
# tcpdump -i eth1 'udp port 53'
To display 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, enter:
# tcpdump 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'
To display all FTP session to 202.54.1.5, enter:
# tcpdump -i eth1 'dst 202.54.1.5 and (port 21 or 20'
To display all HTTP session to 192.168.1.5:
# tcpdump -ni eth0 'dst 192.168.1.5 and tcp and port http'
Use wireshark to view detailed information about files, enter:
# tcpdump -n -i eth1 -s 0 -w output.txt src or dst port 80

#15: strace – System Calls

Trace system calls and signals. This is useful for debugging webserver and other server problems. See how to use to trace the process and see What it is doing.

#16: /Proc file system – Various Kernel Statistics

/proc file system provides detailed information about various hardware devices and other Linux kernel information. See Linux kernel /proc documentations for further details. Common /proc examples:
# cat /proc/cpuinfo
# cat /proc/meminfo
# cat /proc/zoneinfo
# cat /proc/mounts

17#: Nagios – Server And Network Monitoring

Nagios is a popular open source computer system and network monitoring application software. You can easily monitor all your hosts, network equipment and services. It can send alert when things go wrong and again when they get better. FAN is “Fully Automated Nagios”. FAN goals are to provide a Nagios installation including most tools provided by the Nagios Community. FAN provides a CDRom image in the standard ISO format, making it easy to easilly install a Nagios server. Added to this, a wide bunch of tools are including to the distribution, in order to improve the user experience around Nagios.

18#: Cacti – Web-based Monitoring Tool

Cacti is a complete network graphing solution designed to harness the power of RRDTool’s data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense for LAN-sized installations up to complex networks with hundreds of devices. It can provide data about network, CPU, memory, logged in users, Apache, DNS servers and much more. See how to install and configure Cacti network graphing tool under CentOS / RHEL.

#19: KDE System Guard – Real-time Systems Reporting and Graphing

KSysguard is a network enabled task and system monitor application for KDE desktop. This tool can be run over ssh session. It provides lots of features such as a client/server architecture that enables monitoring of local and remote hosts. The graphical front end uses so-called sensors to retrieve the information it displays. A sensor can return simple values or more complex information like tables. For each type of information, one or more displays are provided. Displays are organized in worksheets that can be saved and loaded independently from each other. So, KSysguard is not only a simple task manager but also a very powerful tool to control large server farms.

Fig.05 KDE System GuardFig.05 KDE System Guard {Image credit: Wikipedia}

See the KSysguard handbook for detailed usage.

#20: Gnome System Monitor – Real-time Systems Reporting and Graphing

The System Monitor application enables you to display basic system information and monitor system processes, usage of system resources, and file systems. You can also use System Monitor to modify the behavior of your system. Although not as powerful as the KDE System Guard, it provides the basic information which may be useful for new users:

  • Displays various basic information about the computer’s hardware and software.
  • Linux Kernel version
  • GNOME version
  • Hardware
  • Installed memory
  • Processors and speeds
  • System Status
  • Currently available disk space
  • Processes
  • Memory and swap space
  • Network usage
  • File Systems
  • Lists all mounted filesystems along with basic information about each.
Fig.06 The Gnome System Monitor applicationFig.06 The Gnome System Monitor application

Bonus: Additional Tools

A few more tools:

  • nmap – scan your server for open ports.
  • lsof – list open files, network connections and much more.
  • ntop web based tool – ntop is the best tool to see network usage in a way similar to what top command does for processes i.e. it is network traffic monitoring software. You can see network status, protocol wise distribution of traffic for UDP, TCP, DNS, HTTP and other protocols.
  • Conky – Another good monitoring tool for the X Window System. It is highly configurable and is able to monitor many system variables including the status of the CPU, memory, swap space, disk storage, temperatures, processes, network interfaces, battery power, system messages, e-mail inboxes etc.
  • GKrellM – It can be used to monitor the status of CPUs, main memory, hard disks, network interfaces, local and remote mailboxes, and many other things.
  • vnstat – vnStat is a console-based network traffic monitor. It keeps a log of hourly, daily and monthly network traffic for the selected interface(s).
  • htop – htop is an enhanced version of top, the interactive process viewer, which can display the list of processes in a tree form.
  • mtr – mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool.