Double condition

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# 1  
Old 07-29-2011
Double condition

I trying to prevent user from entering empty string and alphabet, but i can do only on of either one cannot seem to make a double condition =.= Any one can help me?? Thank in advance

while expr "$sold" : "[a-z]*" > /dev/null ;	#check for int
echo "Number only!"
echo "No. of copies sold  : "
read sold

while [ "$sold" = "" ]
echo "Error! Please enter a value!"
echo "value : "
read sold

# 2  
Old 07-29-2011
if `echo $sold` | grep -vq '^[0-9][0-9]*$'  || test -z "$author; then
  echo 'not number in $old or zero length $author" >&2

# 3  
Old 07-29-2011
Erm yazu yours code have the same problem as my, i do not know why but it seem like every time there double condition it will alway have interpretation problem for shell. My code can also work stand along as in with one condition by itself it can work but when i join them up problem occur =.=
# 4  
Old 07-29-2011
What shell?
In dash (posix shell) this code works fine.
# 5  
Old 07-29-2011
Code: line 260: syntax error near unexpected token `fi' line 260: `fi '

i also using dash(posix shell)

Last edited by radoulov; 07-29-2011 at 01:40 PM.. Reason: Code tags, please!
# 6  
Old 07-29-2011
You could try something like this (the code accepts only integers):

while printf 'Number of copies sold: '; do
  read sold
  case $sold in
      ( *[!0-9]*|"" ) 
	    printf >&2 'Invalid input: %s\n' "$sold"  ;;
      ( * ) 
	    break                                     ;;	

# proceed with the value of $sold here ...

# 7  
Old 07-29-2011
Wow radoulov this work like charm can i ask you something i am actually very new to shell. Why when you set a condition for it to check number you put wild card symptom in front and behind

Last edited by GQiang; 07-30-2011 at 12:44 AM..
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