Day No. 1
---------
What is an OS
It is a program which controls hardware
(cpu, ram, hard disk, nic, keyboard, mouse, terminal)
What are the common OS in the market
UNIX (
WIndows (XP, 7, 8, )
2000, 2003, 2008, 2012
MacOS - Mac (Apple)
OS/400 (IBM) - AS/400
MainFrame (IBM)
Theory : UNIX History
AT &T, Bell Labs, C - 1967
AIX (IBM),
Solaris (Sub)
HP-UX (HP)
IRIS (Silicon Graphics)
DEC (Digital)
Linux - x86 - Intel, AMD (open source)
Linux Distros (Red Hat, SuSe, CentOS, Fedora, Ubuntu)
Open Source
License, Subscription
Command : echo
echo "Hello world"
echo 'Hello world'
echo Hello world
echo Hello world
echo 'Hello world'
echo -e '\n\nHello\nWorld\n'
echo -e '\n\nHello\tWorld\n'
Command : clear
Command : alias
alias cls='clear'
alias
unalias cls
Note: alias will last only for a session
Shortcuts : ctrl + l
Command : whoami
Command : id
Display UID, GID of promary group and GIDs of all seconday groups
Command : date
date -s to set the time of the server - can be run as root
What is a UNIX date : 01-01-1970
date +%D
date +%Y
date +%m
date +%d
date +%d.%m.%Y
date +%d-%m-%Y
Command : cal
cal
cal 1960
cal 5 2014
Command : uname
uname
uname -r
uname -a
Note: architecture,64bit/32it,machinename,
Command : man
man date
man crontab
man 5 crontab
man -k keyword
Command : ifconfig
ifconfig
Note: ip addr, mac addr, netmask, name of ethernet card given by SA
Command : uptime
Command : who
Command : w
Note: JCPU, PCPU, IP Address, What
Command : users
Command : hostname
hostname -s
Command : history
history -c
export HISTSIZE=5000
Note: These commands are stored in a file named .bash_history
!20 <== execute 20th command from your history
ctrl + r <== search at the command prompt
Command : exit
Shortcuts : ctrl + d
Command : ping
ping yahho.com
ping -c2 192.168.0.254
Command : ssh
ssh aaftab@172.24.0.240
ssh -l aaftab 172.24.0.240
ssh -X aaftab@172.24.0.240 <== For opening graphical commands (firefox)
Command : last
Command : write
Command : wall
Shortcuts : ctrl + shift + n
Shortcuts : ctrl + shift + t
Shortcuts : ctrl + shift + +
Enlarge font
Shortcuts : ctrl + -
Reduce font
Shortcuts : up arrow
previous command
Shortcuts : down arrow
next command
Day No. 2
---------
Command : pwd
Command : cd
cd <== goes to your home dir
cd .. <== goes to your parent dir
cd . <== . mean current directory
cd ~ <= goes to your home dir
cd ~aaftab <= goes you aaftab's home directory
cd ~aaftab/bin <= goes to bin directory which is under aaftab's home dir
cd / <== go to the top most dir
cd - <== go to previous directory
Theory : Filesystem (Directory structure)
/
/bin
/etc
/home
/sbin
/root
/tmp
/usr/bin
Command : ls
ls -l <= long listing sorted from a-z
name
time on which the file/dir was last modified
size of a file/dir
group owner
owner/user
no of links
permissions ( owner, members of group owner, others)
file type (- file, d dir, l link, s socket, c char device, b block device)
devcices (mouse, keyboard, disks, disk partition, terminal/window, usb)
ls -a <== all - mean show hidden files (hidden file starts with a .)
ls -t <== list of files sorted by time
ls -r <== list of files sorted by i reverse order
ls -i <== Display inode number of each file
ls -l .
ls -l $HOME
ls -l ~
ls -l ..
ls -l ../..
ls -l ~oracle
ls -ld /home/aaftab <== display the info of the direcrory and not what is inside that directory
Theory : What is inode (index Node). It is structure. A table with info of a file
name, timestamps, owner, group owner, perm, size,
Symbol : ?
Symbol : *
Command : cat
cat /home/arununix/dir1/abhi.txt
cat abhi.txt
cat ./abhi.txt
cat -n abhi.txt
cat -n /etc/passwd
Command : su
su - arununix <== will ask you arununix's password
su - root <== will ask you root's password
su - <== will ask you root's password
Command : more
more /etc/passwd
space bar <== display next page
enter key <== display next line
Command : less
less /etc/passwd
space bar <== display next page
enter key <== display next line
/aaftab <== search the word 'aaftab' in the file
q <== exit from the file
Command : head
head /etc/passwd <== display top 10 lines of /etc/passwd file
head -6 /etc/passwd <== display top 6 lines of /etc/passwd file
Command : tail
tail /etc/passwd <== display last 10 lines of /etc/passwd file
tail -6 /etc/passwd <== display last 6 lines of /etc/passwd file
tail -f /etc/passwd <== display last few lines contineously
tail -n +2 /etc/passwd <== display all lines from bottom except the top two
Command : touch
Command : cp
cp /etc/passwd /home/aaftab/mypasswd
cp /etc/passwd ./mypasswd
cp /etc/passwd . <= . means pwd
cp /etc/passwd ./bin
cp /etc/passwd bin <== same as above because i im in my home dir
cp /etc/passwd /tmp
cp ../../etc/passwd .
cp /etc/passwd $HOME
cp /etc/*.conf $HOME
cp -i /etc/passwd /tmp
cp -r bin binbac
cp -r ./bin ~/binback
cp -r ./bin ~arununix
cp ~oracle/*.sh ~/bin
Theory : What is a shell script & how to execute it
Command : file
Command : set <== display values of user & system defined variables
Command : env <== display values of system defined variables
Command : stat
Command : wc
wc -l <== display total number of lines in a file
wc -w <== display total number of words in a file
wc -c <== display total number of characters in a file
Command : mv <== rename a file or to move a file ( cut paste)
mv a.txt b.txt
mv /home/shekahr/a.txt /home/aaftab/b.txt
mv $HOME/a.txt b.txt
mv ~/a.txt ~aaftab/b.txt
mv ./a.txt ./b.txt
mv a.txt /tmp
mv a.txt /tmp/b.txt
mv ~arununix/.bash_profile ~
mv ~oracle/*.sh ~/bin
mv /home/aaftab/bin /home/shekahr/binbak
mv /home/aaftab/bin/* /home/shekahr
Command : rm
rm a.txt
rm -i a.txt
rm -f a.txt
rm *.sh
rm $HOME/*.txt
rm ~oracle/*.sh
rm /tmp/*.tmp
rm -r ./bin <== remove bin directory
rm -r $HOME/bin <==remove bin directory
rm -r /home/aaftab/bin <== remove bin directory
rm -f /tmp/a.txt
rm -i /tmp/a.txt
Command : mkdir
mkdir /home/aaftab/newbin
mkdir ~/newbin
mkdir newbin
mkdir ./newbin
mkdir ~oracle/newbin
mkdir $HOME/newbin
mkdir /tmp/aaftab
Command : rmdir
rmdir /home/aaftab/bin <== remove dir if it is empty
Symbol : ~
Symbol : .
Symbol : ..
Theory : Client Server Concepts
Servers: sshd(22), vsftpd (21), httpd(80) dns(53)
Daemon is a constantly running program in the background
Note: File related commands (ls, cat, more, less, wc , cp, mv, touch,
Note: Dir related commands (ls,
Day No. 3
---------
Command : man
man -k keyword
SEE ALSO
Command : whatis
whatis ls
Command : whereis
whereis cp
Command : which
which cp
Command : tar
tar -c -f /tmp/aaftab.tar /home/shekahr
tar -x -f /tmp/aaftab.tar -C /tmp/new
tar -t -f /tmp/aaftab.tar
tar -c -z -f /tmp/aaftab.tar.gz /home/shekahr
tar -x -f /tmp/aaftab.tar.gz -C /tmp/aaftab
tar -c -f /tmp/aaftab_26_06_2014.tar $HOME
tar -c -f /tmp/aaftab_26_06_2014.tar ~
Command : gzip
gzip abcd.txt
gzip /tmp/abcd.tar
Command : gunzip
gunzip abcd.txt.gz
gunzip abcd.tar.gz
gunzip /tmp/abcd.tar.gz
Command : zip
zip abcd.txt.zip abcd.txt
Command : unzip
unzip abcd.txt.zip
Command : vi
3 modes - command (Esc) , typing mode (insert) , Ex Mode
Type - insert (below current line - o , above current line)
i - insert before current position
a - insert after the current position
o - below the current line
O - above the current line
delete (word, line, multiple lines, char)
dw - delete a word
dd - delete the current line
9dd - delete 9 lines below the current, including the current line
D - delete from the current position till the end of line
x - delete a current character
copy (word, line, ...)
yw - copy current word
yy - copy current line
9yy - copy 9 lines including the current line
paste (above the current line, below current line, at the end of the line)
p - paste clipboard below current line
P - paste clipboard above current line
undo
u - undo previous changes
search (above the current cursor location, below the current cursor location)
/aaftab <== search the word aaftab below current position
?aaftab <== search the word aaftab above current position
n - to goto next occurence of the searched word
replace
:1,20s/aaftab/peter/ <== replace aaftab by peter from line 1 till 20
replace only the first occurence of word aaftab
:1,40s/aaftab/peter/g <== replace aaftab by peter from line 1 till 40
replace all occurences of word aaftab in these lines
:1,$s/aaftab/peter/g <== replace aaftab by peter in the entire file
replace all occurences of word aaftab in entire file
:%s/aaftab/peter/g <== replace aaftab by peter in the entire file
replace all occurences of word aaftab in entire file
r <== replace a current character
cw <== change the current word
redo
. <== redo the previous command
save
:w <== save
:w! <== save even if the file is read only
(you must be the owner of the file)
close/exit/quit - quit without saving
:q <== quit
:q! <== quit without saving
show line numbers
:set nu
:set nonu
goto - begining of file , end of file, to spacific line,
start of line, end of line
up , dkkkkwn , right, left
gg <== gkkkk to the begining of the file
G <== end kkkkf the file
:5 <== gkkkk to line number 5
^ <== go to start of the current line
$ <== go to the end of the current line
j <== down arrow
k <== up arrow
l <== right arrow
h <== left arrow
page up
ctrl b < ==pageup
page down
ctrl f <== pagedown
bring contents from other file to the current file
:r a.txt <== bring contents of a.txt into current file at the current cursor location
Day No. 4
---------
Command : sort
cat data.txt
aaftab Pune 99
Sachin Parbhani 9000
Sanyam Satara 888
sort data.txt
sort /home/aaftab/UNIX/data.txt
sort -r /home/aaftab/UNIX/data.txt
sort -k2 /home/student/Desktop/data.txt
sort -r -k2 /home/student/Desktop/data.txt
sort -k2 -r /home/student/Desktop/data.txt
sort -rk2 /home/student/Desktop/data.txt
sort -k3 /home/student/Desktop/data.txt
sort -k3 -n /home/student/Desktop/data.txt
sort -r -n -k3 /home/student/Desktop/data.txt
sort -rnk3 /home/student/Desktop/data.txt
aaftab:Pune:99
Sanyam:Satara:888
Sachin:Parbhani:9000
sort -n -t: -k3 data.txt
sort -n -t':' -k3 data.txt
Command : uniq
uniq data.txt
Command : cut
cut -d":" -f1 data.txt
cut -d":" -f2 data.txt
cut -d":" -f1,3 data.txt
cut -d":" -f1-3 data.txt
cut -d'a' -f2 data.txt
cut -d' ' -f3 data.txt
cut -d' ' -f3 /home/student/data.txt
File : /etc/passwd
stores user info on your system
1. username
2. password (always x)
3. UID
4. GID
5. Name or info of user
6. home directory of the user
7. login shell <= shell program automatically starts when user logs in
cut -d':' -f1 /etc/passwd
cut -d':' -f1,6 /etc/passwd
Command : fgrep , grep, egrep
grep aaftab data.txt
grep -i aaftab data.txt
grep -v aaftab data.txt
What is a regular expression :
It is a search pattern used by commands like grep, egrep, sed, etc to search a specific pattern of characters in a file
Regular expressions
. <== any single char
* <== zero or multiple occurances of a previous char
^aaftab <== aaftab word is at the begining of the line
aaftab$ <== aaftab is at the end of the line
[abc] <== either a or b or c
[^p] <== any char other than p
[a-z] <== any char from a to z
[A-Z] <== any char from A to Z
^$ <== blank line
[0-9] <== any single digit
[086] <= either 0 or 8 or 6
[^086] <= neither 0 nor 8 nor 6
Extended Regular expression
egrep '(aaftab|peter)' data.txt <== show all line those contain either aaftab or peter
grep -E '(aaftab|peter)' data.txt <== show all line those contain either she khar or peter
Command : diff
Command : tr
echo 'aaftab Tulshibagwale | tr -s ' '
Command : cmp
io redirection: cmd 1> filename
io redirection: cmd 1>> filename
1> filename <== created a blank file
What is a /dev/null file
There is a file named null in /dev/ directory. Anyone has the write permission on this file. Any data written or redirected to this file is immediately erased. This file, therefore, can be used for collecting garbage.
io redirection: cmd | cmd
cut -d':' -f1 /etc/passwd | sort
ls -l | sort -n -k5 | tail -1
ls -l /etc | sort -n -k5 | tail -1
who | cut -d' ' -f1 | sort | uniq
io redirection: &>
io redirection: 2>>
io redirection: 2>
tar -cvf /tmp/a.tar /etc 1> a.txt
tar -cvf /tmp/a.tar /etc 2> b.txt
tar -cvf /tmp/a.tar /etc &> c.txt
Command that need input
cat, wc, sort, more, less, grep, fgrep, egrep, head, tail, sed
io redirection: <
Note: stdout is a virtual file sttting in RAM. You cannot see this file using
ls command. The file descriptor for this file is 1.
Day No. 5
---------
Ad Practicals : No 1
Ad Practicals : No 2
Ad Practicals : No 3
Day No. 6
---------
Theory : permissions, groups, users
Command : id
id <= displays uid and gid of currently logged in user
id oracle <==displays uid and gid of user oracle
Command : groups
groups <== displays all groups that you are a member o (first group is the primary group)
groups oracle <== displays all groups that the user oracle is a member of
FIle : ~/.bash_logout
FIle : ~/.bash_profile
FIle : ~/.bash_history
FIle : ~/.bashrc
FIle : ~/.vimrc
File : /etc/group <== list of all groups
Command : chgrp
chgrp dba a.txt <== changes the group owner of a.txt file to dba
Command : chmod
Only owner/root can run the chmod command on a file/directory
u=owner/user g=group o=other a=all
- <== remove the permission
+ <== give the permission
chmod g+x $HOME
chmod go-rwx $HOME
chmod a+rwx $HOME <= be careful when you run this command
chmod a-rwx a.txt
chmod u+rwx,g+rx a.txt
r - 4
w - 2
x - 1
chmod 444 a.txt
chmod 421 a.txt
chmod 621 a.txt
chmod 700 a.txt
chmod 750 a.txt
chmod 755 a.txt
chmod 777 a.txt
chmod -R 755 $HOME
chown
chown arung a.txt <== chown can be executed by root only
changes the owner of a.txt file to arung
chown arun.dba a.txt <== changes owner to arun and group owner to dba
chown arun:dba a.txt <== changes owner to arun and group owner to dba
chown -R arun:dba /home/aaftab <== changes owner to arun and group owner to dba of all file and subdirectories inside /home/aaftab
Shortcuts : ctrl + d
Day No. 7
---------
Command : ps
ps
ps -e <== shows everything i.e. all processes on your system
ps -f <== full listing i.e. give more info of process
ps -ef
ps aux <== give cpu and ram info of each process
IMP fields (owner, pid, ppid, comm, %CPU, %MEM)
Command : pstree <== shows parent child relationships between processes
Command : top
Command : free
Swap mean virtual ram. It is not real ram. It is some space on hard disk
Swap = page file in windows
Swap can be a file on a hard disk or it can be a partition on the harddisk
File : /proc/meminfo
Command : mpstat
File : /proc/cpuinfo
Command : iostat
Command : bg
Command : fg <== bring the background job to foreground. The background job
may be running or stopped.
Status :
Running & attched to terminal - Running in the foreground
Running in background
Stopped
Command : jobs <== display list of jobs started from the termonal
Command : sleep
Command : kill
kill 8188 <== kill i.e. terminate the process with 8188 PID
kill -9 8188 <== forceful/sure kill if the process cannot be killed by the above command
Command : lsof <== display list of opened files
lsof
lsof -u aaftab <== all files opened by aaftab (can be run by root)
lsof -p 1881 <== shows all files opened by process 1881
Symbol : &
Shortcuts : ctrl + c
Shortcuts : ctrl + z
Day No. 8
---------
Command : nslookup
Command : nmap
Command : netstat
Command : bc
Command : dnsdomainname
Command : scp
Command : ftp
Command : lftp
Command : sftp
Command : wget
Command : rsync
Day No. 9
---------
Command : crontab
Note: crontab is a command which interacts with a daemon named crond.
Daemon is a constantly running process in the background. The daemon process
is not attached to the termminal. i.e. TTY is ?. This crond daemon is
automatically started when your server is booted. You can check if this
process is running or not by typing the following command
ps -ef | grep crond
service crond status
The purpose of this daemon process is to wake up every minute and
check if there are any programs/scripts that need to be executed on behalf of
some user. A program/script scheduled to run at a specific time is called as a
job. In other words crond is reponsible for running jobs on your system.
The crontab command is the way to tell crond about which
program/script to run at which time and at which interval.
crontab -l <== see the existing job schedule
crontab -r <== remove the existing job schedule (dengerous command)
crontab -l > crontab.backup <== output of crontab -l is stored in crontab.backup file
crontab < crontab.newfile <== Schedule eritten in crontab.newfile is sent as an input to the crontab command
Explain each and every entry in crontab file.
The time and date fields are:
field allowed values
----- --------------
minute 0-59
hour 0-23
day of month 1-31
month 1-12 (or names, see below)
day of week 0-7 (0 or 7 is Sun, or use names)
A field may be an asterisk (*), which always stands for "first-last".
Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen. The speci-
fied range is inclusive. For example, 8-11 for an "hours" entry specifies execution at hours
8, 9, 10 and 11.
Lists are allowed. A list is a set of numbers (or ranges) separated by commas. Examples:
"1,2,5,9", "0-4,8-12".
Step values can be used in conjunction with ranges. Following a range with "<number>" speci-
fies skips of the number’s value through the range. For example, "0-23/2" can be used in the
hours field to specify command execution every other hour (the alternative in the V7 standard
is "0,2,4,6,8,10,12,14,16,18,20,22"). Steps are also permitted after an asterisk, so if you
want to say "every two hours", just use "*/2".
Command : find
find command is used to find a file/s in a specific directory (Note: grep is used to find a word/string in a file/s)
find - search for files in a directory hierarchy
Syntax :
find which_dir [criteria] action
--------- ----------- -------
A file whose name is a.txt and print it on the terminal
find /home -name a.txt -print
A file whose name is a.txt, A.txt, A.TXT and print it on the terminal
find /home -iname a.txt -print
A file whose owner is aaftab and print it on the terminal
find /home -user aaftab -print
Find in either /home or /etc a file whose owner is aaftab and print it on the terminal
find /home /etc -user aaftab -print
Find in /home a file whose groupowner is oinstall and list the file details like the ls command
find /home -group oinstall -ls
Find in /home a files whose permission is 777 and list the file details like the ls command
find /home -perm 777 -ls 2> /dev/null
+10 10 -10
<-----------------------------------------|---------------------|
5 15
(Today)
Find files in /home whose modification time is exactly 7 days ago
find /home -mtime 7 -print
Find files in /home whose modification time is before 7 days
find /home -mtime +7 -print
Find all log files in /tmp whose modification time is before 7 days and delete them
find /tmp -mtime +7 -name '*.log' -delete
Find files in /home whose modification time is within last 7 days
find /home -mtime -7 -print
find /home -atime <== access time
Find files in /home whose size is 10M (you can use K M G T)
find /home -size 10M -print
Find files in /home whose size is greater than 10M
find /home -size +10M -print
find / -user oracle -size +100M -ls 2> /dev/null
Find files in /home whose size less is 10M
find /home -size -10M -printo
find /home -newer a.txt -exec rm {} \;
find /home -newer a.txt -exec cp {} /tmp \;
find /home -newer a.txt -exec mv {} /tmp \;
find /home -newer a.txt -exec chmod 700 {} \;
find /home -newer a.txt -exec chown oracle.oinstall {} \;
find /home -newer a.txt -exec grep aaftab {} \;
find /home -newer a.txt -exec wc -l {} \;
find /etc -name '*.conf' -exec cp {} /mybakup \;
find /etc -name '*.conf' -exec cp {} /mybakup/{}.bak \;
tar -cvf /tmp/a.tar /home/aaftab/a.sh /home/aaftab/b.sh /home/aaftab/c.sh
tar -cvf /tmp/a.tar `find /etc -name '*.conf' -print`
find /home -empty
find /home -gid 100
find /home -uid 200
find /home -newer a.txt -print
find /home -newer a.txt -ls
find /home -newer a.txt -delete
find /home -newer a.txt -ok
find /home -newer a.txt -ok -exec rm {} \;
find /home -inum 27772 -print
Some examples of find commands :
# touch file_{1,2,3}
# touch FILE_{1,2,3}
# touch file_{pune,mumbai,nagpur}
1> find /home/aaftab -name "file_pune -print
------------ ----------------- -----------
where to find What to find What action to take on this file
2> find . -name "file_?"
3> find $HOME -name "file_*"
4> find /etc -name "*.conf"
5> find /usr -name "*.gz"
7> find / -user lp -name a.txt 2> /dev/null
8> find /var -user root -group mail -print 2> /dev/null
9> find /var/lib -user rpm -group rpm -ls 2> /dev/null | less
10> find /etc/httpd -exec file {} \;
11> find /etc/mail -name "sendmail*" -exec file {} \;
12> find /etc -name "*.conf" -exec cp {} {}.bak \;
13> find /etc -name *.conf.bak -ok rm {} \; # -ok is like -exec, but asks user for confirmation
14> find /tmp -type f -ls 2> /dev/null
15> find /tmp -type d -ls 2> /dev/null
17> find /etc -type l -ls 2> /dev/null | wc -l
18> find /var/lib -user games -ls 2> /dev/null | less
19> find /bin /usr/bin/ /sbin -perm -u+s -ls 2> /dev/null
20> find /etc/httpd/conf -ok file {} \;
21> tar -cvf etc.tar $(find /etc -name "*.conf" )
22> find /etc -name passwd > /tmp/output_of_find
23> find /etc -name squid.conf >> /tmp/output_of_find 2> /dev/null
24> find $HOME -mtime +7 -print
25> find $HOME -mtime -7 -print
Command : ln
Command : mail
mail <== check the email inbox (1, d 2, d * )
mail aaftab@gmail.com (. means end of email)
mail -s 'Hello' aaftab@gmail.com < /etc/passwd
mail -s 'Hello' aaftab@gmail.com -a b.txt < /dev/null
Day No. 10
---------
Command : rpm
rpm -qa
rpm -qa | grep nmap
rpm -q
rpm -qi
Command : ssh-copy-id
Command : ssh-key-gen
Command : vmstat
Test : No 10
Q: Which command is used to find information about already installed software
rpm -q package_name (e.g rpm -q nmap)
rpm -q software_name
Q: How to get the detailed info of the vsftpd software/package
rpm -qi vsftpd
Q: What version of httpd software has been installed on your system
rpm -q httpd
Q: How to find all packages installed on your system
rpm -qa (a means all)
Q: Is perl or python installed on your system
rpm -qa | grep perl
rpm -qa | grep python
Q: What is the version of perl
rpm -qi perl
Q: have you installed 64 bit or 32 bit version of python
rpm -q python <== look for x64
Q: Which command creates publc and private keys
ssh-keygen
Q: In which dir these keys are stored
$HOME/.ssh
Q: What are the permissions on the private key
rw-------
Q: WHich algorithm is used to encrypt these keys
RSA
Q: How to put your public key in some other user's account
ssh-copy-id student@192.168.0.2
The above command will copy your public key in student's account
on 192.168.0.2 machine. The password of student will be asked.
Q: Where is the public key stored in student's account
~student/.ssh/authorized_keys
Q: How to execute a command on another machine
ssh student@192.168.0.2 'hostname'
Day No. 11
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Ad Practicals : No 1
Ad Practicals : No 2
Ad Practicals : No 3
Day No. 12
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Final test (Theory + Practicals)
