if then else structure - UNIX for Dummies Questions & Answers

props · #1 (**permalink**) 12-27-2003

echo name the file that you want to read
read answer

if [ $# = 0 ]
then
echo you must enter a file name

fi
cat $answer

im trying to catch the error if user forget to enter the name of the file

anyone can help me ?
thanks

jayakhanna · #2 (**permalink**) 12-27-2003

Code:

echo "Enter answer"
read answer

echo $answer | od -b

if [ "$answer" = "" ]
then
        echo "You must enter a file name"
        exit 1
else
        cat $answer
fi

Regards
JK

added code tags for readability --oombera

props · #3 (**permalink**) 12-27-2003

% sh mmm
Enter answer
fileX
0000000 146 151 154 145 130 012
0000006
cat: cannot open fileX

jayakhanna this is what comes up if you run the code

jayakhanna · #4 (**permalink**) 12-27-2003

I am really sorry I was just checking the octal value for \n.
Okay any how the program should be like this

echo "Enter answer"
read answer

if [ "$answer" = "" ]
then
echo "You must enter a file name"
exit 1
else
cat $answer
fi

Well from your mail I think your concern is that you want to check whether the particular file exists or not, Am i right. If so then
use the below code after *read answer* in the above code

Code:

if [ ! -s $answer ]
then
     echo "The file does not exist"
     exit 1
fi

Regards
JK

added code tags for readability --oombera

props · #5 (**permalink**) 12-27-2003

no worries now the program works fine!!!

aprecciate your help

Happy New Year

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