Count the Number of Files
find . -type f | wc -l
Empty a File
echo > filename
>FileName
Tail Last Tailed File
!tail
Find and Remove Files Matching
a pattern
find $PWD -type f -name
"*Jul-*.ESS-A1.log" -exec rm -f {} \;
Find and Zip files matching a
Pattern
find $PWD –type f –name
“ess_admin.controllermessages.log.” | xargs tar zcvf one.tar
Differences between 2 files in
remote hosts
diff <(ssh alice cat
/etc/apt/sources.list) <(ssh bob cat /etc/apt/sources.list)
Find the Symbolic Link
readlink -f LinkFIle
Monitor the active thread count
of a process (jvm) on linux
Dev:vx1423:djbs002-bin $ ps uH
-p 10343 | wc -l
40
Show Process belong to all
Users
ps -ef | grep java
Password Generator
echo "my Password" |
md5sum
Find the Command Line Of the
Process
ps ux : find the Process ID
cd /proc/<pId of Process>
cat cmdline
List all the Jars loaded by a
Process
lsof -p <PID> | grep jar
All process Running as a
Specific User
pgrep -l -f -x -u root
Search The File From Multiple
Jar Files
find . -name "*.jar"
| xargs -tn1 jar tvf | grep --color "log4j.xml"
Show Ports that belong to this
PID
netstat --all --program | grep
<PID>
Find Time Zone Of the System
date +%Z
Drop all the Connections
available now for a Port
iptables -I INPUT -p tcp -dport
80 -j DROP
Find from which package the
tool is provided
yum provides /bin/ls
Find all the Specific Process
ps -fp $(pgrep -d, -x java)
List all files starting with
dots
ls -ld .[1-9A-Z]*
Reverse A String
rev<<<"This is a
test"
Find and Grep a File
find $PWD -type f -exec egrep
PAVAN {} \;
Find the Time took Process To
Complete
/usr/bin/time -v
<command>
Memory Information ( Much
Better than Free Command)
vmstat -s -S M | grep mem
Find the Process Based On
Command
ps -f -C java
See the Memory Usage of Process
ps aux --sort pmem ( See the
MEM column)
find out which cpu processor a
process is running on
ps -eo pid,args,psr
Return Number of kernel Threads
Owned by a process
ps -o thcount –p
Display Date of the Process
Started
ps -o lstart
List Threads By PID along with
Thread Start Time
ps -o lwp,lstart --pid
<PID>
Find Information of the Parent
Process
ps -o ppid= | xargs ps -p
<PID>
Count Threads OF a JVM Process
ps uH p | wc –l
Print a stack trace of a
running process
Pstack <PID>
Find how many files and application
is using
lsof +c 0 | cut -d' ' -f1 |
sort | uniq –c
Find and Kill a Process
Ps ux | grep | grep –v grep |
awk ‘{print $2}’ | xargs –r kill -9
Print Lines Between 404 and 487
sed -n '404,480p' <File
Name>
List all files opened by a
particular command
lsof -c java
Determine if port is open or
not
lsof -i :22
Kill a Process on the Port
kill -9 `lsof -t -i
:port_number`
List all files opened by a
particular command
lsof -c java
Check open ports
lsof -Pni4 | grep LISTEN
View details of network activity
lsof -i :7000-8000
show the working directories of
running processes
lsof -bw -d cwd -a -c java
find the deleted file ,which is
in use
lsof -n |grep delete
Grep from Open Files
lsof | grep "stuff"
View Open File Descriptors for
a Process
lsof -p | wc -l
Find The Command Line Of the
Process Using Specific Port
cat /proc/$(lsof
-ti:631)/cmdline
Find out what is listening on a
series of ports
/sbin/fuser -n tcp {7000..8000}
Get the 10 Biggest Files
du -sh * | sort -n | tail
Convert Of Bytes to Mbs
units --terse "3415014314
bytes" "MB"
SSh and Execute a Command
ssh root@<Remote Machine>
-q 'echo $MYDIR’
Find out which process is using
up your memory using ps, awk, sort.
ps aux | awk '{if ($5 != 0 )
print $2,$5,$6,$11}' | sort -k2n
Create Multiple Files at a Time
touch $(seq -f
"file%02g" 10)
Find Whether The Process is
32Bit or 64Bit
file -L /proc/<PID>/exe
The Output would be some thing
like this
/proc/6462/exe: ELF 32-bit LSB
executable, Intel 80386, version 1 (SYSV), for GNU/Linux 2.2.5, dynamically
linked (uses shared libs), not stripped
Find Whether a port is open on
a Remote Host
nc -z <Ip Address>
<port>; echo $?
1
1:Running and Open
0:No
Last Boot Time
who -b
system boot May 31 23:59
Find the Operating System Type
cat /etc/issue
tmpwatch
Remote Files which havenot been
accessed for a period of Time
tmpwatch -umc -v 24 /test :
Delete Files that are not accessed under 24 hours
Show Ports that Belong to a
Process
netstat --all --program | grep
<PID>
HostIP
/usr/bin/gethostip www.google.com
www.google.com 74.125.227.50
4A7DE332
Find the File Permission of a
file
stat –printf="%a\n"
<File Name>
Execute a Script on the Remote
Host
ssh <User ID>@<Host
Name> 'sh' < $PWD/<Script Name>
M4 : Replace
This command takes an input
file and substitutes strings inside it with the parameters passed, similar to
substituting for variables. For example, here is an input file:
$ cat temp
The COLOR fox jumped over the
TYPE fence.
Were you to substitute the
strings "COLOR" by "brown" and "TYPE" by "broken",
you could use:
$ m4 -DCOLOR=brown
-DTYPE=broken temp
The brown fox jumped over the
broken fence.
Else, if you want to substitute
"white" and "high" for the same:
$ m4 -DCOLOR=white -DTYPE=high
temp
The white fox jumped over the
high fence.
Status Of the HTTP
curl -o /dev/null --silent
--head --write-out '%{http_code}\n' <url>
200
-o /dev/null throws away the
usual output
-silent throws away the
progress meter
-head makes a HEAD HTTP
request, instead of GET
-write-out '%{http_code}\n'
prints the required status code
Number Of Active Physical
Processors
Dev:vx1423:djbs002-~ $ cat
/proc/cpuinfo | grep physical.id | sort -u | wc -l
2
Number of CPU cores per
Processor
If this number is 1 and
physical CPUs is 2, then each of the 2 physical processors has 1 CPU cores,
leading to a total of 2 cores.
Dev:vx1423:djbs002-~ $ grep
cpu.cores /proc/cpuinfo | sort -u
cpu cores : 1
Number of Logical Processors
For each processor core that is
physically present, the operating system addresses two virtual or logical
cores, and shares the workload between them when possible. The main function of
hyper-threading is to decrease the number of dependent instructions on the
pipeline
Dev:vx1423:djbs002-~ $ grep
processor /proc/cpuinfo | wc -l
2
Find Whether a Port is Open On
a Remote Machine
nmap -p 16162 vx1528
Interesting ports on
eth0.vx1528.uprr.com (67.206.10.243):
PORT STATE SERVICE
16162/tcp open unknown
Find OS and Other Information
about a Remote Host
[root@vx111a ~]# nmap -O
172.16.11.178
Starting Nmap 4.11 (
http://www.insecure.org/nmap/ ) at 2013-03-19 18:52 IST
Interesting ports on
172.16.11.178:
Not shown: 1672 closed ports
PORT STATE SERVICE
25/tcp open smtp
80/tcp open http
135/tcp open msrpc
139/tcp open netbios-ssn
443/tcp open https
445/tcp open microsoft-ds
1026/tcp open LSA-or-nterm
3389/tcp open ms-term-serv
MAC Address: 00:25:64:BB:D8:66
(Unknown)
Device type: general purpose
Running: Microsoft Windows
2003/.NET|NT/2K/XP
OS details: Microsoft Windows
2003 Server or XP SP2
Finding Allocations of Memory
For a Proces
pmap -x <PID>| grep rwx |
sort -n -k3 | less
List Process By memory usage
ps -e -orss=,args= | sort -b
-k1,1n | pr -TW$COLUMNS
List all the Installed Perl
packages
perl -MFile::Find=find
-MFile::Spec::Functions -Tlwe 'find { wanted => sub { print canonpath $_ if
/\.pm\z/ }, no_chdir => 1 }, @INC'
Total Number of Process that
Can Be Created
RHEL 2.1 RHEL-3 RHEL-4 RHEL-5 RHEL-6
Max number of processes 11000
32000 32000 32000 32768[1]
RHEL6: [1] default and limit on
32 bit kernels. On 64 bit kernels, limit is 4194304, configurable via
/proc/sys/kernel/pid_max
All Open Tomcat Threads
Dev:vx11111:jbs002-~ $ ps -ALcf
| grep org.apache.catalina.startup.Bootstrap | wc -l
87
ac - print statistics about
users connect time
Dev:vx1111:jbs002-jas $ ac -p
jbs002 37.60
pma002 0.02
root 170.69
jbs001 841.64
total 1049.95
Convert horizontal lines to
vertical lines
Dev:vx1379:djbs002-jas $ echo
"123456"| fold -w 11
123456
Shows the Java Process along with
Command Line
pgrep -fl java
Find The MAC Address
[root@vx111a test]# cat
/sys/class/net/eth0/address
00:25:64:b3:19:fd
Find The Command Line Of the
Process Using Specific Port
cat /proc/$(lsof
-ti:631)/cmdline
Ping a Host Using Specific
Interface ( Or can check Internet Connection for an Interface)
ping -I eth0 www.yahoo.com
Scp To transfer a File
Scp /root/file1
root@10.5.11.193:.
‘.’ Says to the root folder. You can use /tmp or any thing to copy
to a specific location
scp -r /dir root@10.5.11.193:. ( Copies a Entire
Directory Structure)
Delete a File
Unlink fileName
Describe a Command
[root@vx111a ~]$ type ls
ls is aliased to `ls
--color=tty'
DMI table Decoder
[root@vx111a ~]# dmidecode
-type bios
Invalid type keyword: ype
Valid type keywords are:
bios
system
baseboard
chassis
processor
memory
cache
connector
slot
ex: dmidecode –type memory :
Prints memory relegated things
Last Reboot Information
[root@vx111a ~]# last reboot
reboot system boot
2.6.18-238.el5 Mon Jul 30 12:44 (06:45)
reboot system boot
2.6.18-238.el5 Fri Jul 27 12:39 (06:36)
reboot system boot
2.6.18-238.el5 Thu Jul 26 13:38 (06:59)
reboot system boot
2.6.18-238.el5 Fri Jul 20 13:03 (06:29)
wtmp begins Tue Jul 3 15:22:01
2012
Files Opened By Application
In Order to find the files that
are opened by an application we can use the lsof command like,
[root@vx111a bin]# lsof +f |
head
COMMAND PID USER FD TYPE DEVICE
SIZE NODE NAME
init 1 root cwd DIR 8,8 4096 2
/
How do I find how many files an
application is using
In order to find how many files
and application is using , we can use
lsof +c 0 | cut -d' ' -f1 |
sort | uniq –c
Find Out What Partition a File
Belongs To
We can use the df command to
find out what partition a file belongs,
[root@vx111a perl]# df -T file1
Filesystem Type 1K-blocks Used
Available Use% Mounted on
/dev/sda7 ext3 49594196 5499736
41534504 12% /
Check the Multi Cast Address
Subscribed
There are times where we need
to test various address including the multi cast address.To find the multi cast
address that was subscribed for the system we can use
[root@vx111a local]# ip maddr
1: lo
inet 224.0.0.1
2: eth0
link 01:00:5e:00:00:fb
link 01:00:5e:00:00:01
inet 224.0.0.251
inet 224.0.0.1
Total Number Of Threads In a
Linux Process
For a single-threaded process,
you will find all the information about the state of the process under
/proc/pid itself. For a multi-threaded process, the /proc/pid will have a sub
directory called task. This directory contains contains one sub directory per
thread, including the main thread: /proc/pid/task/tid1, /proc/pid/task/tid2,
etc. The main thread has the thread ID same as the process ID.
The easiest way to find out if
a given process is multi threaded or not is to examine the /proc/pid/task
directory. If it contains many sub directories, its a multi-threaded process.
Otherwise, it could be a single threaded one.
The Number of Threads that
processes have can be given using
cat /proc/<PID>/status
Working Directory of a Current
Process
There are many times for a sys
admin or even a developer to get the current working directory of a process. We
can get this information by visiting /proc/pid/cwd or even by using pwdx
command.
According to the man pages, a
pwdx command provides the information of the working directory of a process.
If we need to find the current
working directory of a process 3349, we can use
[root@vx111a local]# pwdx 3349
3349: /root
Or We can also use
[root@vx111a local]# cat
/proc/$(lsof -ti:3349)/cmdline
ro root=LABEL=/ rhgb quiet
Find and Kill a Process
There are some times where we
need to find a process and kill it in a single line , here is how it can be
done
Ps ux | grep | grep –v grep |
awk ‘{print $2}’ | xargs –r kill -9
Find the Command Line Of a
Process
Dev:vx1379:djbs002-7996 $
/usr/bin/strings /proc/7728/cmdline
/software/java32/jdk1.6.0_16/bin/java
-Djbs.name=JAS-A2
-server
-Xms512m
-Xmx512m
-XX:MaxPermSize=256m
-Dcom.sun.management.jmxremote.port=10009
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
-Djava.security.auth.login.config=/config/jboss/ews/1.0/domains/jas/JAS-A2/conf/login.config
-Djbs.logdir=/logs/jboss/ews/1.0/domains/jas
-javaagent:/software/jboss/ews32/1.0/lib/spring-agent.jar
.
.
start
Scheduler class for a process
in linux
ps ax --format uname,pid,ppid,tty,cmd,cls,pri,rtprio
Details about Process
ps -fp $(pgrep -d, -x java)
ps -ef : This output shows that the first process
that is executed when the system boots
Highest CPU
ps -eo pcpu,pid,user,args |
sort -k 1 -r | head -10 | awk "{ print $2 }"
Tar file correctly Copied or
Not
tar -ztf
/path/to/archive.tar.gz > /dev/null && echo $? If echo $? = 0
Memory Usage
sar -q 1 | tail -1 | awk '{
print "" $3}' | sed 's/%//g'
Finding the CPU Threshold
top -b -n 1 | awk -F'[:,]'
'/^Cpu/{sub("\\..*","",$2); print $2}'
Current User With Session Count
who |
awk '
{ User [$1]++; }
END { for (i in User) printf
"%-9s %s\n", i, User [i] }
Top 10 Process
ps -efF "%x %p %P %U %u %y
%a" | sort -r | head
Memory Space Details
free -t -m | grep
"Total" | awk '{ print "Total Memory space : "$2 "
MB";
print "Used Memory Space :
"$3" MB";
print "Free Memory :
"$4" MB";
}'
Swap memory Details
free -t -m | grep
"Swap" | awk '{ print "Total Swap space : "$2 "
MB";
print "Used Swap Space :
"$3" MB";
print "Free Swap :
"$4" MB";
}'
Remove Files Using Find
Dev:vx1111:bs002-jas $ find .
-type f -atime +60 -print > ./deadFiles
Dev:vx1111:bs002-jas $ cat
./deadFiles
./JAS-B2/conf/logs/juli.2010-02-11.log
./JAS-B2/bin/logs/juli.2010-01-06.log
./JAS-B2/bin/logs/juli.2009-11-05.log
./JAS-B2/bin/logs/juli.2010-02-11.log
./JAS-C2/catalina.out
./JAS-C2/conf/catalina.out
Dev:vx1111:bs002-jas $ rm `cat
./deadFiles`
How to Find Files That Exceed a
Specified Size Limit
find . -size +400 -print
How to List the Newest Files
ls -t
Most recently Created or
Changed
ls -tl
List Process By memory usage
ps -e -orss=,args= | sort -b
-k1,1n | pr -TW$COLUMNS
Find how many Files are opened
for a process
lsof -p <PID> | wc -l
741
Detailed Information
Dev:vx1379:djbs002-~ $ ps -fp
$(pgrep -d, -x java)
UID PID PPID C STIME TTY TIME
CMD
djbs002 20366 1 0 May13 ?
00:01:03 /software/java32/jdk1.6.0_16/bin/java -Djbs.name=JAS-B2 -server
-Xms512m -Xmx512m -XX:MaxPermSize=256m -Dcom.sun.management.jmxre
View What PID is Touching
lsof -p PID Or lsof -p 2424
Also, /proc/PID/ provides lots
of info:
Code:
cd /proc/2324
ls –l
Finally, you can attach PID to
a file and record all calls:
strace -s 2000 -p PID -o
/tmp/pid.log
If you just need to trace a lib
calls, try ltrace.
Total number of unique users logged
in currently
cat /tmp/a| sed '1,2d' | awk
'{print $1}' | uniq | wc -l
List of unique users logged in
currently
cat /tmp/a | sed '1,2d'| awk
'{print $1}' | uniq
User who is using high %cpu
cat /tmp/a | sed '1,2d' | awk
'$7 > maxuid { maxuid=$7; maxline=$0 }; END { print maxuid, maxline }'
Smallest to Largest
Dev:vx1379:djbs002-~ $ ls -s |
sort -nr | more
View Command Line
Dev:vx1379:djbs002-7996 $
/usr/bin/strings /proc/7728/cmdline
/software/java32/jdk1.6.0_16/bin/java
-Djbs.name=JAS-A2
-server
-Xms512m
-Xmx512m
-XX:MaxPermSize=256m
-Dcom.sun.management.jmxremote.port=10009
Show Number of Java Process
top -b -n 1|grep java|wc -l
processes per user counter
Dev:vx1379:djbs002-jas $ ps hax
-o user | sort | uniq -c
2 avahi
1 dbus
.
.
Cpu & Memory Usage
ps aux --sort=%mem,%cpu
Who Started this process
Dev:vx1379:djbs002-jas $ ps -o
comm= -p $(ps -o ppid= -p 28453)
init
How Much Ram Is Being Used
Dev:vx1379:djbs002-jas $ ps -o
rss -C java | tail -n +2 | (sed 's/^/x+=/'; echo x) | bc
2245952
Find When a Process Was Started
Dev:vx1379:djbs002-jas $ ps -o
lstart 28453
STARTED
Fri May 3 16:41:01 2013
Print ENVIRONMENT
Variables associated with a Process
ps ewwo command <PID> |
tr ' ' '\n' | grep \=
List Threads by Pid along with
Thread Start Time
Dev:vx1379:djbs002-jas $ ps -o
pid,lwp,lstart --pid 28453 -L
PID LWP STARTED
28453 28453 Fri May 3 16:41:01
2013
28453 28455 Fri May 3 16:41:01
2013
28453 28456 Fri May 3 16:41:01
2013
..
Show CPU usage for EACH cores
djbs002-jas $ ps ax -L -o
pid,tid,psr,pcpu,args | sort -nr -k4| head -15 | cut -c 1-90
26903 5658 0 0.1
/software/java64/jdk1.6.0_24/bin/java -Dprogram.name=run.sh -Dapp.nam
..
Memory Usage
Dev:vx1379:djbs002-jas $ ps -o
comm,%mem,args 28453
COMMAND %MEM COMMAND
java 1.8
/software/java64/jdk1.6.0_24/bin/java
Total CPU Usage Percentage
omhq126a:dwls999-~ $ ps aux |
awk {'sum+=$3;print sum'} | tail -n 1
261.4
DF in Cloumn Format
df -hP|column -t
Show the working directories of
running processes
Dev:vx1379:djbs002-~ $ lsof -bw
-d cwd -a -c java
COMMAND PID USER FD TYPE DEVICE
SIZE/OFF NODE NAME
java 9582 djbs002 cwd DIR 253,2
1024 6149 /config/jboss/ews/1.0/domains/jas
java 26417 djbs002 cwd DIR
253,9 4096 131093 /privdir/djbs002
Find the Class File in jars
Dev:vx1379:djbs002-lib $ find .
-name "*.jar" | while read line; do unzip -l $line; done | grep
AlgDH.class
486 03-26-10 14:20
com/tera/tdgss/jalgapi/AlgDH.class
Java Path
Dev:vx1379:djbs002-lib $ ls -l
$(type -path -all java)
-rwxr-xr-x 1 djvm999 jvmgrp
47308 Jul 31 2009 /software/java32/jdk1.6.0_16/bin/java
Discard Ping Output
ping
-c 1 $host >/dev/null || { echo " The remote Host is unavailable"
; exit; }
Extract the tar and bz2 file at same time
tar
jxf firefox-bin.tar.bz2
Get response from a URL
wget
--spider -nv -T 5 -t 1 http://localhost:10011/instance-monitor
Get the Socket Status
Dev:vx1379:djbs002-~ $ netstat -t -n | cut -c 68- | sort | uniq -c
| sort -n
1
1 State
4 ESTABLISHED
Test the RPM
rpm
-i --test eject-1.2-2.i386.rpm
List File descriptors
used by process
lsof -Fpcn -u djhe002 | awk '
/^p/ { pid=substr($0,2) }
/^c/ { cmd=substr($0,2) }
/^n/ {
fd[cmd"["pid"]"]++ }
END { for (cc in fd) printf("%-20s
%i\n",cc,fd[cc]) } ' | sort -n -k 2
File currently Open For writing
lsof
| grep -e "[[:digit:]]\+w"
Get the Socket Status
netstat -anl | awk '/^tcp/ {t[$NF]++}END{for(state in t){print
state, t[state]} }'
CLOSE_WAIT 429
Happy learning
