Unix in a Nutshell, 4th Edition

Name

for

Synopsis

    for ((init; cond; incr))
    do
     commands
    done

Bash and ksh93 . Arithmetic for loop, similar to C’s. Evaluate init. While cond is true, execute the body of the loop. Evaluate incr before retesting cond. Any one of the expressions may be omitted; a missing cond is treated as being true.

Example

Search for a phrase in each odd chapter:

    for ((x=1; x <= 20; x += 2))
    do
            grep $1 chap$x
    done