For loop shell script with no list or terminating condition?

Question

Just saw this in a script at my internship. I've googled but for the life of me I cannot figure out what kind of for loop this is.

 # Declare variables for use
 35   args=$*
 36   noofargs=$#
 37   isjavapassed="false"
 38   isjavavalid="false"
 39   argsarray=""
 40   d64option=""
 41
 42  varcount=0;
 43  for tempvar
 44  do ....

how does this for loop work? it is literally just for tempvar? where is the terminating condition or the list it iterates over? There is nothing above this but comments. Any help is much appreciated. Thank you.

Community · Accepted Answer · 2020-06-20 09:12:55Z

3

From the Bash Reference Manual section on Looping Constructs:

The syntax of the for command is:

for name [ [in [words …] ] ; ] do commands; done

Expand words, and execute commands once for each member in the resultant list, with name bound to the current member. If ‘in words’ is not present, the for command executes the commands once for each positional parameter that is set, as if ‘in "$@"’ had been specified (see Special Parameters). The return status is the exit status of the last command that executes. If there are no items in the expansion of words, no commands are executed, and the return status is zero.

So that's a case where "in words" is missing and so it loops over the positional parameters.

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered Jun 16, 2015 at 19:19

Etan Reisner

81.7k8 gold badges120 silver badges154 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Rakholiya Jenish · Accepted Answer · 2015-06-16 19:25:43Z

1

Basic for syntax is:

for arg in [list]
do
 command(s)...
done

Omitting the in [list] part of a for loop causes the loop to operate on $@ -- the positional parameters.

Try running the below script with and without arguments:

for a
do
 echo -n "$a "
done

SOURCE Example 11-6

answered Jun 16, 2015 at 19:25

Rakholiya Jenish

3,25321 silver badges29 bronze badges

Collectives™ on Stack Overflow

For loop shell script with no list or terminating condition?

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related