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Full Discussion: While Loop Syntax help needed
Top Forums Shell Programming and Scripting While Loop Syntax help needed Post 302335460 by kshji on Sunday 19th of July 2009 12:26:32 PM
Old 07-19-2009
Simple syntax:
Code:
while command_exit_code_is_zero
do
    somecmd1
    somecmd2
done

-lt, -gt, ... are options of test command, look shell builtin test (= also [ ] )

After while is some command line, shell will do it, check exit code and if it's 0 = okay, then do the command lines between do and done.

while true
while cp x y
while (( i < 100 ))
while [ "$some" -lt 100 ]
while test "$some -lt 100
while [ "$some" = "1" ]
while read line
while :
...
: is command, which is builtin and give always exit 0 status ( shell's nop command), do nothing. Today also true and false are builtin commands, so those are more "readable" as :

You can break the loop using command break.

You can jump to the while line using command continue.
ex.
Code:
while read line
do
      case "$line" in
           "") continue  ;;    # next line
           end*) break ;;     # end this while
      esac
      do_some_for "$line"
done

 

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LEARN ABOUT DEBIAN

paps

PAPS(1) 						      General Commands Manual							   PAPS(1)

NAME

       paps - UTF-8 to PostScript converter using Pango

SYNOPSIS

       paps [options] files...

DESCRIPTION

       paps reads a UTF-8 encoded file and generates a PostScript language rendering of the file. The rendering is done by creating outline curves
       through the pango ft2 backend.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with  two  dashes  (`-').   A  summary  of  options	is
       included below.

       --landscape
	      Landscape output. Default is portrait.

       --columns=cl
	      Number of columns output. Default is 1.
	      Please notice this option isn't related to the terminal length as in a "80 culums terminal".

       --font=desc
	      Set the font description. Default is Monospace 12.

       --rtl  Do right to left (RTL) layout.

       --paper ps
	      Choose paper size. Known paper sizes are legal, letter and A4. Default is A4.

       Postscript points
	      Each postscript point equals to 1/72 of an inch. 36 points are 1/2 of an inch.

       --bottom-margin=bm
	      Set bottom margin. Default is 36 postscript points.

       --top-margin=tm
	      Set top margin. Default is 36 postscript points.

       --left-margin=lm
	      Set left margin. Default is 36 postscript points.

       --right-margin=rm
	      Set right margin. Default is 36 postscript points.

       --gutter-width=gw
	      Set gutter width. Default is 40 postscript points.

       --help Show summary of options.

       --header
	      Draw page header for each page.

       --markup
	      Interpret the text as pango markup.

       --lpi  Set the lines per inch. This determines the line spacing.

       --cpi  Set the characters per inch. This is an alternative method of specifying the font size.

       --stretch-chars
	      Indicates  that  characters  should be stretched in the y-direction to fill up their vertical space. This is similar to the texttops
	      behaviour.

AUTHOR

       paps was written by Dov Grobgeld <dov.grobgeld@gmail.com>.

       This manual page was written by Lior Kaplan <kaplan@debian.org>, for the Debian project (but may be used by others).

								  April  17, 2006							   PAPS(1)
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