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Full Discussion: if condition in a while loop
Top Forums Shell Programming and Scripting if condition in a while loop Post 302472141 by ygemici on Tuesday 16th of November 2010 11:25:55 AM
Old 11-16-2010
Quote:
Originally Posted by cfajohnson
It's an inefficient way of getting the first three characters of "$line".

It will not do what is wanted if the number of characters before the comma is anything other than 3.

A more efficient (and portable) method uses parameter expansion instead of an external command:
Code:
grp=${line%"${line#???}"}

I dont agree your comment about inefficient way..
Why do you think such as?
Sed is external command but it has same effect every shells.

svajhala already wants process for only first three chars..

Maybe more portable or maybe not..If we hope to do every jobs from shell , it is not exactly true according to me.
 

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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This command is likely to be withdrawn from X/Open standards.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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