shell script help

[1a]

i want to compare two values in shell script .

example-

ca=50

pa=45

if [ $ca -gt $pa ]

i need output greater value . how to print the vaule after the if statement.

[Hakki Aydin Ucar]

 if [ $ca -gt $pa ]
 then
echo $ca
fi

[V. Nyga]

if [ $ca -gt $pa ]
 then
echo $ca
 elif [ $pa -gt $ca ]

 then
echo $pa
 else
echo "They are equal"
fi

(Sorry Hakki) :-)

[Hakki Aydin Ucar]

Danke ! :smileyvery-happy:

I missed the half part of code..

[James R. Ferguson]

Hi:

Since you only want the greater value, or if they are equal, merely that value, you could use:

# [ ${ca} -gt ${pa} ] && echo ${ca} || echo ${pa}

Regards!

...JRF...

[Dennis Handly]

If you are using a real shell you can use C style expressions:

if (( ca > pa )); then

   echo $ca

else

   echo $pa

fi

This prints the maximum of the two.

[1a]

hi every one thanks for you reply

Dennis,

i user your script , it working fine . please tell how to print the greater value in one text file

[1a]

Sorry dennis,

i use your script , it is working fine. please tell how to print the greater value in one text file

because i need output value through mail, so i plan to send mailx command.

[Tom Maloy]

Starting with Dennis' script, and noting that nothing will print if the values are equal, this might work:

if (( ca > pa )); then

   echo $ca

else

   echo $pa

fi   >  max.txt

mailx  -s  "max values"  mail_address_here  <  max.txt

[Dennis Handly]

And if you don't plan to send much text to your message:

if (( ca > pa )); then

   echo $ca

else

   echo $pa

fi  | mailx  -s  "max values"  mail_address_here

>noting that nothing will print if the values are equal:

The above fragment always prints a value.

[James R. Ferguson]

Hi:

No matter which script you like ( and we'll use Dennis's since you reference his ), consider learning a Unix philosophy that says do-one-thing-and-do-it-well.

The whole script could be:

# cat mymax

#/usr/bin/sh

typeset ca=$1

typeset pa=$2

if (( ca > pa )); then

   echo $ca

else

   echo $pa

fi

...which then could be run to output to your terminal:

# ./mymax 100 99

100

...or to a file:

# ./mymax 100 99 > myoutput

...or to email:

# ./mymax 100 99 | mailx -s "Max Value" mymailaddress

The point is to allow the user to determine where he/she wants the output to appear rather than hard-coding that assumption into your script.

Regards!

...JRF...

[1a]

Hi dennis,

if the values are equal , how to print the value.

[1a]

hi james R.

thanks for your reply. i want to learn shell script .please send any pdf document or ppt

[Dennis Handly]

>if the values are equal, how to print the value.

Is this a new question?

Otherwise my script fragment will print the maximum of the two and always prints, even if equal.

If you only want to print if they are equal:

if (( ca == pa )); then

   echo $ca

fi

[James R. Ferguson]

---

@1a wrote:

thanks for your reply. i want to learn shell script .please send any pdf document or ppt

---

I used to recommend the "HP-UX Shell User's Guide" which was a nice overview of the various shells.  With the advent of the "improved" (NOT!) HP websites, this doesn't appear to be available anymore.

Regardless, there are any number of good books on shell scripting.  Find one for beginners and begin.  I urge you to confine your initial learning to the Korn ('ksh') or Bash ('bash') shell rather than the dysfunctional C shell.  In HP-UX, the default shell is simply called 'sh' and is a Korn variant.  Bash can also be installed on HP-UX though it is usually the standard for most Linux distributions.

Part of learning to write code (in any language) is *writing* and *reading*.  A very good collection of shell scripts is available here:

http://www.shelldorado.com/

Regards!

...JRF...

[Stephan.]

I only have a pretty old copy of the shell user's guide but it's still a pretty good one.

Find it attached.

hth,

Stephan