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Full Discussion: Bash script error problem
Top Forums Shell Programming and Scripting Bash script error problem Post 302455234 by methyl on Tuesday 21st of September 2010 06:30:52 AM
Old 09-21-2010
You may consider restructuring the script to separate the parameter validation from the processing such that the script has a beginning a middle and an end.
The actual error is caused by trying to use $num which has no value. We can prevent this by checking the value of $# first. Because there is more than one reason to reject the command line we can prepare the "usage" string in advance. In the original script the "|grep usage" has no use .
Just as an aside, your shebang line contains a lot of trailing blanks and an extra blank between the hash and /bin/bash.

Code:
#!/bin/bash
argcount=$#     # Number of arguments
num="$1"        # Value of parameter 1
usage='usage: ./area <query> ...'       # Usage string

######################
# Parameter validation
######################
if [ ${argcount} -ne 1 ]
then
        echo "${usage}"
        exit
fi
#
if [[ $num -gt 99 && $num -lt 1000 ]]
then
    :
else
    echo "${usage}"
    exit
fi

########################
# Processing starts here
########################
echo Area Codes for '"'$num'"':
grep "^$num" ~cs155/pub/area-codes | sed 's/^/   /'

########
# End
########
echo "good night"

 

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Num(3o)                                                            OCaml library                                                           Num(3o)

NAME
Num - Operation on arbitrary-precision numbers. Module Module Num Documentation Module Num : sig end Operation on arbitrary-precision numbers. Numbers (type num ) are arbitrary-precision rational numbers, plus the special elements 1/0 (infinity) and 0/0 (undefined). type num = | Int of int | Big_int of Big_int.big_int | Ratio of Ratio.ratio The type of numbers. === Arithmetic operations === val (+/) : num -> num -> num Same as Num.add_num . val add_num : num -> num -> num Addition val minus_num : num -> num Unary negation. val (-/) : num -> num -> num Same as Num.sub_num . val sub_num : num -> num -> num Subtraction val ( */ ) : num -> num -> num Same as Num.mult_num . val mult_num : num -> num -> num Multiplication val square_num : num -> num Squaring val (//) : num -> num -> num Same as Num.div_num . val div_num : num -> num -> num Division val quo_num : num -> num -> num Euclidean division: quotient. val mod_num : num -> num -> num Euclidean division: remainder. val ( **/ ) : num -> num -> num Same as Num.power_num . val power_num : num -> num -> num Exponentiation val abs_num : num -> num Absolute value. val succ_num : num -> num succ n is n+1 val pred_num : num -> num pred n is n-1 val incr_num : num Pervasives.ref -> unit incr r is r:=!r+1 , where r is a reference to a number. val decr_num : num Pervasives.ref -> unit decr r is r:=!r-1 , where r is a reference to a number. val is_integer_num : num -> bool Test if a number is an integer === The four following functions approximate a number by an integer : === val integer_num : num -> num integer_num n returns the integer closest to n . In case of ties, rounds towards zero. val floor_num : num -> num floor_num n returns the largest integer smaller or equal to n . val round_num : num -> num round_num n returns the integer closest to n . In case of ties, rounds off zero. val ceiling_num : num -> num ceiling_num n returns the smallest integer bigger or equal to n . val sign_num : num -> int Return -1 , 0 or 1 according to the sign of the argument. === Comparisons between numbers === val (=/) : num -> num -> bool val (</) : num -> num -> bool val (>/) : num -> num -> bool val (<=/) : num -> num -> bool val (>=/) : num -> num -> bool val (<>/) : num -> num -> bool val eq_num : num -> num -> bool val lt_num : num -> num -> bool val le_num : num -> num -> bool val gt_num : num -> num -> bool val ge_num : num -> num -> bool val compare_num : num -> num -> int Return -1 , 0 or 1 if the first argument is less than, equal to, or greater than the second argument. val max_num : num -> num -> num Return the greater of the two arguments. val min_num : num -> num -> num Return the smaller of the two arguments. === Coercions with strings === val string_of_num : num -> string Convert a number to a string, using fractional notation. val approx_num_fix : int -> num -> string See Num.approx_num_exp . val approx_num_exp : int -> num -> string Approximate a number by a decimal. The first argument is the required precision. The second argument is the number to approximate. Num.approx_num_fix uses decimal notation; the first argument is the number of digits after the decimal point. approx_num_exp uses scien- tific (exponential) notation; the first argument is the number of digits in the mantissa. val num_of_string : string -> num Convert a string to a number. === Coercions between numerical types === val int_of_num : num -> int val num_of_int : int -> num val nat_of_num : num -> Nat.nat val num_of_nat : Nat.nat -> num val num_of_big_int : Big_int.big_int -> num val big_int_of_num : num -> Big_int.big_int val ratio_of_num : num -> Ratio.ratio val num_of_ratio : Ratio.ratio -> num val float_of_num : num -> float OCamldoc 2012-06-26 Num(3o)
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