Shell Programming and Scripting

Hi, from the man page (man wc):

Code:

If no files are specified, the standard input is used and no file name is
     displayed.

By using <, the input to the command is standard input (stdin, which is redirected from the file).

Expanding on what Scrutinizer said...

When the wc utility is given one or more operands, it reads from the named file(s) and prints the number of complete lines in each file and the file's name(s). (If more than one operand is given, it also prints a total line at the end.)

When no operands are given, wc reads from standard input and only prints the number of complete lines it found.

If you don't mind reversing the order (# of lines before file name) and you don't mind the total line at the end, this should be much more efficient:

Code:

#!/bin/sh
cd /data/test/input
wc *.dat >> dat_results.out

Thank You both for the explanation.

I apologize, I omitted an option from the script I suggested earlier. It should have been:

Code:

#!/bin/sh
cd /data/test/input
wc -l *.dat >> dat_results.out

And, of course, you want > instead of >> if you want to replace the previous contents of the output file instead of appending your new results to the end of the existing contents of dat_results.out.