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Top Forums UNIX for Dummies Questions & Answers sed - combination of line deletion and pattern matching Post 302682009 by bakunin on Sunday 5th of August 2012 07:23:45 AM
Old 08-05-2012
Quote:
Originally Posted by Don Cragun
All of the sed documentation I've seen says that the "{" command format is:
Code:
[2addr] {function
function
. . .
}

because "function" doesn't include an address. I wonder if this is something that all implementation of sed do (but never documented) {and should be included in a future version of the POSIX and UNIX standards}, or if it is only provided by some implementations of sed?
"function" is probably meant recursively. A function itself is a list of commands and may contain other functions as well. This is a principle in probably any programming language.

To be honest i haven't read the POSIX standard papers as intensively as you seem to have done, so i can only guess. What i have explained above is true for all the sed-variants i have ran across in my nearly 30 years of Unix, so even if my explanation is not completely POSIXly-correct it seems to cover the truth from a practical point of view.

Still, i would be interested if you could find out how it is really supposed to work as i would prefer to be sure instead of almost sure. It seems like you could shed some light on it.

I hope this helps.

bakunin
 

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fmt(1)								   User Commands							    fmt(1)

NAME
fmt - simple text formatters SYNOPSIS
fmt [-cs] [-w width | -width] [inputfile...] DESCRIPTION
fmt is a simple text formatter that fills and joins lines to produce output lines of (up to) the number of characters specified in the -w width option. The default width is 72. fmt concatenates the inputfiles listed as arguments. If none are given, fmt formats text from the standard input. Blank lines are preserved in the output, as is the spacing between words. fmt does not fill nor split lines beginning with a `.' (dot), for compatibility with nroff(1). Nor does it fill or split a set of contiguous non-blank lines which is determined to be a mail header, the first line of which must begin with "From". Indentation is preserved in the output, and input lines with differing indentation are not joined (unless -c is used). fmt can also be used as an in-line text filter for vi(1). The vi command: !}fmt reformats the text between the cursor location and the end of the paragraph. OPTIONS
-c Crown margin mode. Preserve the indentation of the first two lines within a paragraph, and align the left margin of each subsequent line with that of the second line. This is useful for tagged paragraphs. -s Split lines only. Do not join short lines to form longer ones. This prevents sample lines of code, and other such formatted text, from being unduly combined. -w width | -width Fill output lines to up to width columns. OPERANDS
inputfile Input file. ENVIRONMENT VARIABLES
See environ(5) for a description of the LC_CTYPE environment variable that affects the execution of fmt. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
nroff(1), vi(1), attributes(5), environ(5) NOTES
The -width option is acceptable for BSD compatibility, but it may go away in future releases. SunOS 5.10 9 May 1997 fmt(1)
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