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Full Discussion: IF-Statements not working
Top Forums Shell Programming and Scripting IF-Statements not working Post 302353992 by methyl on Wednesday 16th of September 2009 08:22:15 PM
Old 09-16-2009
Quote:
err=0;

echo "If-Test begins..."
if ! [[ "$err"==1 ]];then
echo "If NOT 0"
fi

if [[ "$err"!=0 ]];then
echo "If NOT (inside braces) 0"
fi

if [[ "$err"==1 ]];then
echo "If 0"
fi

if [[ "$err"==1 ]];then
echo "Using \" for 0"
fi
It would help to know which shell you use.

In general the number of square brackets matters. There is rarely a reason to use "[[ condition ]]" when "[ test ]" would do.

Paraphrasing and decomplicating your code. I have removed surplus semi-colons, moved exclamation marks (meaning NOT), replaced string comparisons "=" with integer comparisons "-eq", and inserted spaces where required. The last two tests are identical, so I have removed the duplicate.
Enjoy.

Code:
# Script starts here
err=0

echo "If-Test begins..."
if [ ${err} -eq 1 ]
then
          echo "If ${err} equals 1"
fi

if [ ! ${err} -eq 0 ]
then
           echo "If NOT (inside braces) ${err} NOT equals zero"
fi

if [ ${err} -eq 1 ]
then
           echo "If (inside braces) ${err} equals one"
fi

Last edited by methyl; 09-16-2009 at 09:24 PM.. Reason: typo
 

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LEARN ABOUT MOJAVE

check_uint32_div

CHECK_INT32_ADD(3)					   BSD Library Functions Manual 					CHECK_INT32_ADD(3)

NAME

     check_int32_add, check_uint32_add, check_int64_add, check_uint64_add, check_int32_sub, check_uint32_sub, check_int64_sub, check_uint64_sub,
     check_int32_mul, check_uint32_mul, check_int64_mul, check_uint64_mul, check_int32_div, check_uint32_div, check_int64_div, check_uint64_div,
     -- detect overflow in arithmetic

SYNOPSIS

     #include <checkint.h>

     int32_t
     check_int32_add(int x, int y, int *err);

     uint32_t
     check_uint32_add(int x, int y, int *err);

     int64_t
     check_int64_add(int x, int y, int *err);

     uint64_t
     check_uint64_add(int x, int y, int *err);

     int32_t
     check_int32_sub(int x, int y, int *err);

     uint32_t
     check_uint32_sub(int x, int y, int *err);

     int64_t
     check_int64_sub(int x, int y, int *err);

     uint64_t
     check_uint64_sub(int x, int y, int *err);

     int32_t
     check_int32_mul(int x, int y, int *err);

     uint32_t
     check_uint32_mul(int x, int y, int *err);

     int64_t
     check_int64_mul(int x, int y, int *err);

     uint64_t
     check_uint64_mul(int x, int y, int *err);

     int32_t
     check_int32_div(int x, int y, int *err);

     uint32_t
     check_uint32_div(int x, int y, int *err);

     int64_t
     check_int64_div(int x, int y, int *err);

     uint64_t
     check_uint64_div(int x, int y, int *err);

DESCRIPTION

     The check_<type>_<operation>(x, y, err) family of functions perform the specified arithmetic operation (addition, subtraction, multiplica-
     tion, or division) with the left operand of x and right operand of y and return the arithmetic result with the specified type.

     Either operand x or y (or both) can be of any type that is compatible to signed or unsigned 8-bit, 16-bit, 32-bit, or 64-bit integers.

     The err argument is or'ed by flags in the function to indicate if an overflow has occurred.  The possible flag values are:

	   CHECKINT_NO_ERROR		   no overflow has occurred
	   CHECKINT_OVERFLOW_ERROR	   overflow has occurred
	   CHECKINT_TYPE_ERROR		   operand is of an incompatible type

     The err argument is not cleared in calls to the check_<type>_<operation>(x, y, err) functions.  Detected overflow persists in the err argu-
     ment until err is reset to CHECKINT_NO_ERROR.

RETURN VALUES

     If successful, the check_<type>_<operation>() functions will return the arithmetic result of performing the operation with left operand x and
     right operand y (even when overflow error occurs).

     If any other error occurs, the return value is -1 and the argument err will be set to indicate the error.

EXAMPLES

	   /* Create a variable to store overflow flag */
	   int32_t err = CHECKINT_NO_ERROR;
	   /* Use checkint API to perform an arithmetic operation and
	    * store result in variable. */
	   int32_t arithmetic_result = check_int32_add(UINT_MAX, 1, &err);
	   /* Check status of overflow flag */
	   if (err & CHECKINT_OVERFLOW_ERROR) {
	       /* Perform overflow resolution code */
	       fprintf(stderr, "Overflow detected!
");
	   }
	   /* Check for type error */
	   else if (err & CHECKINT_TYPE_ERROR) {
	       /* Deal with incompatible types error */
	       fprintf(stderr, "Incompatible types!
");
	   }
	   /* Reset overflow flag for next operation */
	   err = CHECKINT_NO_ERROR;

ERRORS

     The check_<type>_<operation>() functions may fail if:

	   [CHECKINT_TYPE_ERROR]	   operand is of an incompatible type

HISTORY

     The checkint() API was introduced in Mac OS X 10.5.

BSD
								  April 20, 2007							       BSD
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