Shell Script

[root@test test1]# echo $HOME
/root
[root@test test1]# echo $USER
root
[root@test test1]#


[root@test test1]# cat sayH.sh
echo " Type your first name"
read fname
echo "MY first name is" $fname
[root@test test1]#



How to change a color in shell script

Black="\[\033[0;30m\]"        # Black
Red="\[\033[0;31m\]"          # Red
Green="\[\033[0;32m\]"        # Green
Yellow="\[\033[0;33m\]"       # Yellow
Blue="\[\033[0;34m\]"         # Blue
Purple="\[\033[0;35m\]"       # Purple
Cyan="\[\033[0;36m\]"         # Cyan
White="\[\033[0;37m\]"        # White

Red="\[\033[1;31m\]"          # Bold Red
Red="\[\033[4;31m\]"          # Underline in Red
echo -e "\n\n ${Red}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${Green}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${Yellow}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${Blue}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${Purple}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${Cyan}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"
echo -e "\n\n ${White}.................Copying user.sh to /etc/profile.d. This will set timestamp format for command history .....${NC}"


How to change line and output

[root@test test1]# echo -n "Do not output the trailing new line"
Do not output the trailing new line[root@test test1]#

[root@test test1]# echo -e "Do not output the trailing new line"
Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "\a Do not output the trailing new line"
 Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "\b Do not output the trailing new line"                                                                                                           Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "\c Do not output the trailing new line"
[root@test test1]#

[root@test test1]# echo -e "\n Do not output the trailing new line"

 Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "\r Do not output the trailing new line"
 Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "\t Do not output the trailing new line"
Do not output the trailing new line
[root@test test1]#

[root@test test1]# echo -e "An apple a day keeps away \a\t\tdoctor\n"
An apple a day keeps away doctor

How to exper use :-
==================================================================
[root@test test1]#

[root@test test1]# expr 1 + 3
4
[root@test test1]# expr 2 - 1
1
[root@test test1]# expr 10 / 2
5
[root@test test1]# expr 20 % 3
2
[root@test test1]# expr 10 \* 3
30
[root@test test1]# echo `expr 6 + 3`
9
[root@test test1]#

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

[root@test test1]# cat nestedif.sh
#osch=0

echo "1. Unix (Sun Os)"
echo "2. Linux (Red Hat)"
echo -n "Select your os choice [1 or 2]? "
read osch

if [ $osch -eq 1 ] ; then

     echo "You Pick up Unix (Sun Os)"

else #### nested if i.e. if within if ######
         
       if [ $osch -eq 2 ] ; then
             echo "You Pick up Linux (Red Hat)"
       else
             echo "What you don't like Unix/Linux OS."
       fi
fi
[root@test test1]#

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

[root@test test1]# cat elf.sh
#
#!/bin/sh
# Script to test if..elif...else
#
if [ $1 -gt 0 ]; then
  echo "$1 is positive"
elif [ $1 -lt 0 ]
then
  echo "$1 is negative"
elif [ $1 -eq 0 ]
then
  echo "$1 is zero"
else
  echo "Opps! $1 is not number, give number"
fi
[root@test test1]#

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

[root@test test1]# cat mtable.sh
#!/bin/sh
#
#Script to test for loop
#
#
if [ $# -eq 0 ]
then
echo "Error - Number missing form command line argument"
echo "Syntax : $0 number"
echo "Use to print multiplication table for given number"
exit 1
fi
n=$1
for i in 1 2 3 4 5 6 7 8 9 10
do
echo "$n * $i = `expr $i \* $n`"
done
[root@test test1]#

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