Inside Solaris™ 9

Repeated-Action Commands

The Bourne shell provides three repeated-action commands, each of which corresponds to constructs you might have seen before in other programming languages:

• for

• while

• until

These commands cause a program to loop or repeat. They are described next.

The for Loop

A useful shell command is the for loop, which is the simplest way to set up repetition in a shell script. The syntax of a for loop is as follows:

for name [ in wordlist . . . ] 
do list 
done 

Each time a for command is executed, name is set to the next word taken from the in word list. If in word . . . is omitted, the for command executes the do list once for each positional parameter that is set. Execution ends when no more words are in the list. The ...