How can I extract digits at the end of a string in UNIX shell scripting? Post: 303026270

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Top Forums Shell Programming and Scripting How can I extract digits at the end of a string in UNIX shell scripting? Post 303026270 by bakunin on Friday 23rd of November 2018 04:34:12 AM

11-23-2018

Registered User

Quote:

Originally Posted by mingch

I tried to create the following scripts but it can't increment the last number from 012 to 013, anyone help? Many thanks.

The reason is that "012" is not a number. "12" is a number and you can increment that to "13". But "012" and "013" are strings and you cannot do calculations with strings.

You haven't told us yet what your shell is and in fact it didn't matter that much because what we did up to now was common ground to all of them. We are leaving this area and maybe i will tell you something you can't use because you have a different shell - which is why you should always state what your environment (OS and shell and their versions most prominently) is.

In Korn shell (ksh) you can use typeset to make a variable have leading zeroes and having a certain length like this (try it on the command line):

Code:

$ typeset -RZ3 variable=12
$ echo $variable
012
$ (( variable += 1 ))
$ echo $variable
013

Variables in shell do not really have a certain "type". Of course it will lead to an error if you try to multiply "abc" by 3 but if you create a string "ab12cd", then somehow (you now know how) get rid of the characters you can multiply the remaining "12" and it will give you "60", which you still can use as a string. What we did above was to create a string, right-aligned (-R) in the length of 3 where every "free"space is filled with zeroes. When we calculate with it like a number, the shell will silently drop the leading zeroes to make the number "12" from "012", then do the calculation and, when writing the result back, realign and refill it (because of the typeset directive, so that "013" is the final content.

I hope this helps.

bakunin

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LEARN ABOUT DEBIAN

grcompiler

grcompiler(1)															     grcompiler(1)

NAME

       grcompiler - Compile GDL into a TrueType Font

SYNOPSIS

       grcompiler [-d] [-D] [-g] [-n number] [-v number] [-w number] [-wall] [-q] gdl-file font-file [output-file] [output-fontname]

Description
       Grcompiler  compiles  a	Graphite Description Language description of the smarts for a font along with a TrueType Font to create a graphite
       font with graphite tables in it.

       -d     Generate XML debugger file.

       -D     Generate all debugger files.

       -g     Permit and ignore invalid glyph definitions.

       -nnumber
	      Set name table start location.

       -q     Quiet mode (no messages except on error).

       -vnumber
	      Set Silf table version number.

       -wnnnn Ignore warning with the given number. This option may be repeated.

       -wall  Display all warnings.

Environment
       grcompiler makes use of the following environment variables

       GDLPP  Specifies the command to execute to run the GDL preprocessor

Files
       gdlerr.txt
	      Warnings and errors are output to this file.

       dbg_classes.txt
	      Debug file that specifies the classes stored in the font in terms of their GDL source and containing glyph ids in hex.

       dbg_cmap.txt
	      Debug file giving Unicode to glyph mapping of all the glyphs in the font and vice versa.

       dbg_enginecode.txt
	      Debug file containing the action code and constraint code associated with each pass and rule in a pass.

       dbg_fsm.txt
	      Debug file that gives the finite state machines of each pass and the rules referenced. For each pass, a  mapping	is  given  between
	      glyph and column number.

       dbg_glyphattrs.txt
	      Debug file containing all the glyph attributes and their names, along with values specified for each glyph.

       dbg_parsetree.txt
	      Debug file giving the complete parse tree of the GDL source file.

       dbg_ruleprec.txt
	      Debug file that lists the rules in precedence order (order in which they will be tested) for each pass.

       $_temp.gdl
	      Debug file containing the output of gdlpp

Author
       Martin Hosken <mhosken@users.sourceforge.net>

							   $Date: 2012-05-29 11:36:50 $ 					     grcompiler(1)

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