Common regular linux command

To find the size of a directory
===============================
du -ch|grep total
du -chs /dir/*

To find the ip of the network
=============================
/sbin/ifconfig

To check the amount of memory
=============================
cat /proc/meminfo | grep MemTotal

To check the amount of swap memory
=============================
cat /proc/meminfo | grep SwapTotal

To check the kernal release of Linux
====================================
uname -a

To check the I/O at the OS level
================================
iostat
vmstat

To find whether Linux machine is 32 or 64 Bit
=============================================
getconf LONG_BIT

To find the OS version in Linux
===============================
cat /etc/redhat-release
cat /etc/issue

To find all users in Linux
==========================
cat /etc/passwd

To find no. of processors in server
===================================
cat /proc/cpuinfo | grep processor | wc -l

to show latest files in a directory
======================
find /dir1 -type f -mtime -1 -name "file*"

To search for a string among the files in a directory, below command for current directory
============================================================
grep -iR "search string" .

find recent files

=================

latest_file=`ssh IP_ADDR_OF_SERVER1 find /dir1 -type f -mtime -1 -name "file*"`

echo Staring SCP of $latest_file from SERVER1 to SERVER2...

/usr/bin/scp user@IP_ADDR_OF_SERVER1:$latest_file /dir2

echo SCP Completed.

ex

===

latest_file=`ssh -p 2022 modn-ldap2.lt.modeln.com  find /archive/pngprd/rman -type f -mtime -1 -name "png*"`

echo Staring SCP of $latest_file from SERVER1 to SERVER2...

/usr/bin/scp -P 2022 rpilla@modn-ldap2.lt.modeln.com:$latest_file .

echo SCP Completed.

delete files older than x days

==============================

find rman*.gz -mtime +90 -exec rm {} \;

find a string in all files and list files

=========================================

grep -H "database" /home/rpilla/purge/*.lis

find files which are more then 100mb in the root directory

==========================================================

find / -xdev -type f -size +100000000c -exec ls -lh {} \;

find / -xdev -type f -size +2000000000c -exec ls -lh {} \;

To delete all files except one

==============================

rm !(filename.txt)

rm  !(file1|file2)

if it does not work on bash then enable as below

shopt -s extglob

To show dates in history

=========================

HISTTIMEFORMAT="%d/%m/%y %T "

Random password generation

==========================

date |md5sum

scp fromdate to todate files

=============================

for i in `find . -type f -ctime -4`

do

scp -P 2022 $i rpilla@modndrdbp05.lt.modeln.com:~

done

split text file into equal lines

================================

split -l 4000 test.txt new

cat new* > newimage.jpg ------to join into a single file

Vi find and replace

=====================

The syntax is as follows:

:%s/WORD-To-Find-HERE/Replace-Word-Here/g

OR

:%s/FindMe/ReplaceME/g