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Top Forums Shell Programming and Scripting Which is the best way/command to do mathematics in UNIX scripting? Post 302403985 by methyl on Monday 15th of March 2010 08:27:03 AM
Old 03-15-2010
Quote:
read lol
read lil
echo "scale=2; $lol - $lil" | bc

A hunch. How did you execute these three lines?

If you type them one-by-one at the command prompt answering each "read" before typing the next command ... they should work.

If you put them in a shell script and execute the script ... they should work.

If you cut/paste all three lines onto the command line they will fail. This is because the second line becomes the input to the first line meaning that $lol contains the string "read lil" which in turn makes the echo contain rubbish to pass to "bc".
 

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line(1) 						      General Commands Manual							   line(1)

NAME
line - read one line from user input SYNOPSIS
timeout] DESCRIPTION
copies one line (up to a new-line) from the standard input and writes it on the standard output. It returns an exit code of 1 on EOF and always prints at least a new-line. It is often used within shell files to read from the user's terminal. Options recognizes the following command-line option: Timeout after timeout seconds where timeout is an integer value (if a non-integer value is specified, it is converted to an integer; i.e., rounded down). A blank is required between and the timeout argument. This option is not documented in POSIX and other industry standards, and should not be used in portable applications. EXTERNAL INFLUENCES
International Code Set Support Single- and multi-byte character code sets are supported. EXAMPLES
The following lines in a shell script prompt for a file name and display information about the file: To limit the response time to 10 seconds, use the form: then test for no response. If no response occurs before timeout expires, a default behavior should be provided. WARNINGS
This command is likely to be withdrawn from X/Open standards. Applications using this command might not be portable to other vendors' sys- tems. As an alternative is recommended. SEE ALSO
sh(1), read(2). STANDARDS CONFORMANCE
line(1)
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