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Top Forums Shell Programming and Scripting Help with awk regular expression for RS record separator Post 303001597 by Don Cragun on Monday 7th of August 2017 09:08:48 PM
Old 08-07-2017
If what you want to do is separate records at points where the last character on a line is a <period>, <question-mark>, or <exclamation-point>, you probably want to use:
Code:
RS="[.?!]$"

as rdrtx1 suggested.

Using RS="[.?!;:]" splits records on <period>, <question-mark>, <exclamation-point>, <semicolon>, and <colon> anywhere on a line.

Using RS="[^\"Mr.\"][.?!]" splits records on any two character sequence where the first character is not a <backslash>, <double-quote>, <uppercase-M>, <lowercase-r>, <period>, <backslash>, or <double-quote> and the second character is a <period>, <question-mark>, or <exclamation-point>. This ERE makes no sense to me for this use.

If, in addition to splitting when a set of characters is found at the end of a line, you also wanted to find that set of characters followed by two <space> characters (which is the common way of separating sentences in old fashioned text files), you could use:
Code:
RS="[.?!](  |$)"

Note that most of the above is talking about gawk and does not necessarily apply to other standards-conforming versions of awk. The standards state that it if more than one character is assigned to RS, it is unspecified whether RS is treated as a multi-character ERE that acts as the record separator or only the 1st character assigned to RS acts as the record separator. If RS is set to an empty string, the record separator is a sequence of two or more adjacent <newline> characters.

The default record separator is a <newline>. When RS is set to something other than a <newline>, <newline> (in addition to whatever FS is set to) is a field separator.
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RLAM(1) 						      General Commands Manual							   RLAM(1)

NAME
rlam - laminate records from multiple files SYNOPSIS
rlam [ -tS ][ -u ][ -iaN | -ifN | -idN | -iiN | -iwN | -ibN ] input1 input2 .. DESCRIPTION
Rlam simply joins records (or lines) from multiple inputs, separating them with the given string (TAB by default). Different separators may be given for different files by specifying additional -t options in between each file name. Note that there is no space between this option and its argument. If none of the input files uses an ASCII separator, then no end-of-line character will be printed, either. An input is either a stream or a command. Commands are given in quotes, and begin with an exclamantion point ('!'). If the inputs do not have the same number of lines, then shorter files will stop contributing to the output as they run out. The -ia option may be used to specify ASCII input (the default), or the -if option may be used to indicated binary IEEE 32-bit floats on input. Similarly, the -id and -ii options may be used to indicate binary 64-bit doubles or integer words, respectively. The -iw option specifies 2-byte short words, and the -ib option specifies bytes. If a number is immediately follows any of these options, then it indi- cates that multiple such values are expected for each record. For example, -if3 indicates three floats per input record for the next named input. In the case of the -ia option, no number indicates one line per input record, and numbers greater than zero indicate that many characters exactly per record. For binary input formts, no number implies one value per record. For anything other than EOL-separated input, the default tab separator is reset to the empty string. A hyphen ('-') by itself can be used to indicate the standard input, and may appear multiple times. The -u option forces output after each record (i.e., one run through inputs). EXAMPLE
To join files output1 and output2, separated by a comma: rlam -t, output1 output2 To join a file with line numbers (starting at 0) and its reverse: cnt `wc -l < lam.c` | rlam - -t: lam.c -t '!tail -r lam.c' To join four data files, each having three doubles per record: rlam -id3 file1.dbl file2.dbl file3.dbl file4.dbl > combined.dbl AUTHOR
Greg Ward SEE ALSO
cnt(1), histo(1), neaten(1), rcalc(1), tabfunc(1), total(1) RADIANCE
7/8/97 RLAM(1)
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