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Top Forums UNIX for Dummies Questions & Answers Need help deciphering this Post 302416821 by Straitsfan on Tuesday 27th of April 2010 09:58:05 PM

04-27-2010

Registered User

Need help deciphering this

I'm reading about command substitutions and came across this little function in my book:

function lsd
{
date=$1
ls -l |grep -i "^.\{42\}$date"|cut -c55-
}

it's a little example which is supposed to select files by modification date, given as an argument to the function.

I can't figure out what the ^, ., and \{42\} means. The book says that the function tells UNIX to match any line that contains 41 characters followed by the function argument, with the date starting in column 42, then only printing the filenames, which start in column 55, but like I said I don't know what these symbols mean (or how they 'translate'). The only thing I've found about the ^ so far is that it's a 'word designator' but I'm not sure if that applies here.

I'm also not sure how to translate the .\{42\} either.

By the way, how do I find out what the column layout for the ls -l command is? (if I've phrased that correctly), that is, what column each part of the listing begins at?

Straitsfan

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LEARN ABOUT DEBIAN

bookman

bookman(1)																bookman(1)

NAME

       bookman - Generate a book from man pages

SYNOPSIS

       bookman [-pPxn] [-o outfile] [-a author] [-d date] [-r release]
       [-t title] [-v volume] [-c coverfile] [manfile]

DESCRIPTION

       bookman	compiles  a  set  of  man  pages files specified by manfile arguments, or if no manfile is given, filenames are read from standard
       input.

OPTIONS

       -p     PDF output format.

       -P     Postscript output format.

       -x     X11 previewing, using gxditview(1).

       -n     no format, output is direct gtroff intermediate format.

       -o outfile
	      Output in file outfile. Default is standard output.

       -a author
	      Set the author, on the cover page.

       -d date
	      Set the date on the cover page.

       -r release
	      Set the book name and release on the cover page.

       -t title
	      Set the title on the cover page.

       -v volume
	      Specify the name of the volume.

       -c coverfile
	      Uses the file coverfile to generate the cover page, i.e. all pages preceding the table of content. coverfile must be in  groff_ms(7)
	      format.

EXAMPLE

       To build a reference manual from section 2 man, do:

	   $ cd /usr/man/man2
	   $ bookman -p -t 'Unix Reference Manual' * >book.pdf

SEE ALSO

       man(1), mandoc(7), groff_ms(7), groff(1), troff(1), grops(1), gxditview(1), ps2pdf(1).

AUTHOR

       Marc Vertes <mvertes@free.fr>

txt2man-1.5.5							   11 April 2011							bookman(1)