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Integer Expressions
The following expressions are used with integers:
Table 27-3: test Integer Expressions
Expression Is True If...
Expression Is True If...
integer1 -eq integer2 integer1 is equal to integer2. integer1 -ne integer2 integer1 is not equal to integer2. integer1 -le integer2 integer1 is less than or equal to integer2. integer1 -lt integer2 integer1 is less than integer2.
integer1 -ge integer2 integer1 is greater than or equal to integer2.
#!/bin/bash
# test-integer: evaluate the value of an integer.
INT=-5
if [ -z "$INT" ]; then
echo "INT is empty." >&2 exit 1
fi
if [ $INT -eq 0 ]; then echo "INT is zero."
else
if [ $INT -lt 0 ]; then echo "INT is negative."
else
echo "INT is positive."
fi
if [ $((INT % 2)) -eq 0 ]; then echo "INT is even."
else
echo "INT is odd."
fi
fi
#!/bin/bash
# test-integer: evaluate the value of an integer.
INT=-5
if [ -z "$INT" ]; then
echo "INT is empty." >&2 exit 1
fi
if [ $INT -eq 0 ]; then echo "INT is zero."
else
if [ $INT -lt 0 ]; then echo "INT is negative."
else
echo "INT is positive."
fi
if [ $((INT % 2)) -eq 0 ]; then echo "INT is even."
else
echo "INT is odd."
fi
fi
integer1 -gt integer2 integer1 is greater than integer2. Here is a script that demonstrates them:
The interesting part of the script is how it determines whether an integer is even or odd. By performing a modulo 2 operation on the number, which divides the number by two and returns the remainder, it can tell if the number is odd or even.