Login or Register to Ask a Question and Join Our Community


UNIX for Dummies Questions & Answers

Conditional ef/elif in scripting

 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers Conditional ef/elif in scripting
# 1  
Old 08-07-2011
Conditional ef/elif in scripting
Hi everyone,

I'm slowly teaching myself shell scripting. I only have one reference book at the momement and i am stuck on a conditional if /elif problem

I have a basic Fahrenheit to Celsius converter script with a condition based on temperature echo output.

There are five conditions, but whenever i run the script it outputs the first and ignores the rest regardless.

Code:
#!/bin/sh
#ftoc.sh
#Usage: To convert Fahrenheit to Celsius
echo "Fahrenheit to Celsius Converter 0.1"
echo         "by Me"
echo "Enter Temperature in Degrees Fahrenheit"
read F
#forumla C=(5/9)*(F-32)
C=$(echo "scale=2;(5/9)*($F-32)" |bc)
echo "$F degress Fahrenheit is = $C degrees Celsius"

if [ "$C -lt 0" ] || [ "$C -ge 50" ]
        then
        echo "Too hot or cold to even think about!"
elif [ "$C -ge 30" ] && [ "$C -lt 50" ]
        then
        echo "Such a HOT DAY!"
elif [ "$C -ge 20" ] && [ "$C -le 30" ]
        then
        echo "That sounds like a pleseant day!"
elif [ "$C -ge 10" ] && [ "$C -le 20" ]
        then
        echo "Ooo, thats a cool day. Better dress warmly"
elif [ "$C -ge 0" ] && [ "C$ -le 10" ]
        then
        echo "SO COLD! I'm staying in today!"
fi

exit

What am I doing wrong here?
# 2  
Old 08-07-2011
You've got your quotes wrong in your conditional expressions.

Code:
if [ "$C -lt 0" ] || [ "$C -gt 50" ]

should be
Code:
if [ "$C" -lt 0 ] || [ "$C" -gt 50 ]

The non-empty string of the first expression will always be true.
# 3  
Old 08-07-2011
Thanks agama Smilie

But now i get an err "integer expression expected" on each elif line (twice on the first)
# 4  
Old 08-07-2011
Then check (with echo "$C") what really you have. Or better add 'set -x' to the beginning of your script (as the second line) and see what happens.
This User Gave Thanks to yazu For This Post:
agama
# 5  
Old 08-07-2011
The output of the top half of the script when provided a number of say 100 (degrees) is calculated to 37.40.

The exact err output i get (in the first instance) is

Code:
./ftoc.sh: line 12: [: 37.40: integer expression expected

# 6  
Old 08-07-2011
Ok. /bin/sh can't work with floating numbers. Truncate them (sed 's/\..*//') or not use scale in bc evaluation, or use bc in test conditions or use awk or ... (a lot).
# 7  
Old 08-07-2011
haha. Thanks yazu.... much to learn, i still have.....
 
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Problem with elif and else

Hello experts, I am having problems with ELIF. Please see the below code : read a; read b; read c; if || || ; then echo "EQUILATERAL" elif || || ; then echo "SCALENE" else echo "ISOSCELES" fi This code works fine for the EQUILATERAL case but fails completely for the... (5 Replies)
Discussion started by: H squared
5 Replies

2. Shell Programming and Scripting

If / elif

Hello all, I have a scenario where I take user input values and accordingly take actions say I run a script with sh scriptname -x GB -e txt (txt can also be text) I have used if clause for the first input (-x GB)and it is working fine Now for second the scenario is if then echo... (3 Replies)
Discussion started by: nnani
3 Replies

3. UNIX for Advanced & Expert Users

if else elif

Hi all,i have configured the following script to check if the file exists or not, #!/bin/sh sleep 30 { FILEFULL=$1`date +$2`* if ; then echo $FILEFULL exist else echo "$FILEFULL File not Found" | mail -s 'server' myaccount@mydomain.com fi } but i have a problem, i need to... (2 Replies)
Discussion started by: charli1
2 Replies

4. Shell Programming and Scripting

elif if not expected

Hi All, I write an script will have some functions... I am getting elif not expected error.. Even tried by using set -x for debug but no use.. Could you please help me out in this Variables .... .... .... TEST_SRC() { cat ${filesrc} >> ${filetgt} if ]; then echo... (12 Replies)
Discussion started by: kmsekhar
12 Replies

5. Homework & Coursework Questions

if/elif help

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: This is my problem for the class. Write a script that asks for the user's age. If it is equal to or higher... (6 Replies)
Discussion started by: aggie6970
6 Replies

6. Shell Programming and Scripting

If, elif, else statements help

I am in need of some help. I am not an advance scripter or programmer, I have novice knowledge. I cannot get a script to work as expected. The script basically does an FTP (which I have work perfectly) and writes to a log. However, I want the script to echo "Not Connected" if the FTP fails to... (2 Replies)
Discussion started by: anthonyon
2 Replies

7. Shell Programming and Scripting

If -elif-else error.

I am getting below error from this code (which is at line 24): if ] #this is line24 in code then mv $File_source_path/$File_name $File_name'_'`date '+%d%m%y'` Error: line 24: Any help with the syntax. I am putting 2 condition with 'AND' clause. This is bash shell. (2 Replies)
Discussion started by: amit.mathur08
2 Replies

8. Shell Programming and Scripting

Query on If-Elif!!

Script Gurus, Need your help in getting this script to come out of logical error : I have pasted the script below: This script finds disk utilzation ... the script is written for both AIX and SUN OS... and option will be given in the initial to select DB or Non DB... its required for my prj...... (1 Reply)
Discussion started by: vangalli
1 Replies

9. UNIX for Dummies Questions & Answers

Help with ELIF statement

I am receiving an elif error on line 13 and I can not figure out the reasoning behind it. I have added the then statement that I was initially missing. Any help would be great. #The purpose of this script is for the end user to be able to enter a positive number #User enters a number NUM=$1... (4 Replies)
Discussion started by: Brewer27
4 Replies

10. Shell Programming and Scripting

If..elif..else...fi

Hi all, I got some problems on executing the following scripts. Scripts: if ]; then echo "M${str}O 0 1" >> ${tempFile} elif ]; then echo "M${str}O 1 0" >> ${tempFile} else echo "M${str}O 0 0" >> ${tempFile} fi Error: "`;' is not expected." what's the problem? (2 Replies)
Discussion started by: Rock
2 Replies
Login or Register to Ask a Question