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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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CSPLIT(1)						    BSD General Commands Manual 						 CSPLIT(1)

NAME
csplit -- split files based on context SYNOPSIS
csplit [-ks] [-f prefix] [-n number] file args ... DESCRIPTION
The csplit utility splits file into pieces using the patterns args. If file is a dash ('-'), csplit reads from standard input. The options are as follows: -f prefix Give created files names beginning with prefix. The default is ``xx''. -k Do not remove output files if an error occurs or a HUP, INT or TERM signal is received. -n number Use number of decimal digits after the prefix to form the file name. The default is 2. -s Do not write the size of each output file to standard output as it is created. The args operands may be a combination of the following patterns: /regexp/[[+|-]offset] Create a file containing the input from the current line to (but not including) the next line matching the given basic regular expression. An optional offset from the line that matched may be specified. %regexp%[[+|-]offset] Same as above but a file is not created for the output. line_no Create containing the input from the current line to (but not including) the specified line number. {num} Repeat the previous pattern the specified number of times. If it follows a line number pattern, a new file will be created for each line_no lines, num times. The first line of the file is line number 1 for historic reasons. After all the patterns have been processed, the remaining input data (if there is any) will be written to a new file. Requesting to split at a line before the current line number or past the end of the file will result in an error. ENVIRONMENT
The LANG, LC_ALL, LC_COLLATE and LC_CTYPE environment variables affect the execution of csplit as described in environ(7). EXIT STATUS
The csplit utility exits 0 on success, and >0 if an error occurs. EXAMPLES
Split the mdoc(7) file foo.1 into one file for each section (up to 20): csplit -k foo.1 '%^.Sh%' '/^.Sh/' '{20}' Split standard input after the first 99 lines and every 100 lines thereafter: csplit -k - 100 '{19}' SEE ALSO
sed(1), split(1), re_format(7) STANDARDS
The csplit utility conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
A csplit command appeared in PWB UNIX. BUGS
Input lines are limited to LINE_MAX (2048) bytes in length. BSD
January 26, 2005 BSD
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