Bash Quick Start Guide

Arithmetic conditions

The POSIX specification for the test and [ commands includes a few arithmetic tests for integers:

• [ "$a" -eq "$b" ]: Equal
• [ "$a" -ne "$b" ]: Not equal
• [ "$a" -lt "$b" ]: Less than
• [ "$a" -le "$b" ]: Less than or equal to
• [ "$a" -gt "$b" ]: Greater than
• [ "$a" -ge "$b" ]: Greater than or equal to

Be careful not to confuse -lt and -gt with < and >; the latter are lexicographic tests, to see whether strings sort after one another. For example, [ 2 \> 10 ] exits successfully, because the "10" string sorts after "2"!

Sometimes using these tests with expansion of arithmetic expressions can be unwieldy to write; for example, if we wanted to test whether the value of the bytes variable, divided by 1,000, was greater than ...