Bash: How to use read with conditions & loops Post: 302983604

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Top Forums Shell Programming and Scripting Bash: How to use read with conditions & loops Post 302983604 by Chubler_XL on Thursday 13th of October 2016 05:25:17 PM

10-13-2016

Moderator

Quote:

Originally Posted by MadeInGermany

You can have more than one line in a while/until condition.
The following uses a code block between until...do plus another explicit code block within {...}

Code:

#!/bin/bash
fetchip() {
  printf "%s: " "$1"
  until
    read
    [[ "$REPLY" =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]] &&
    {
    IFS=. read ip1 ip2 ip3 ip4 <<< "$REPLY"
    [[ $ip1 -le 255 && $ip2 -le 255 && $ip3 -le 255 && $ip4 -le 255 ]]
    }
  do
    printf "Invalid $1 IP address - Please re-enter\n%s: " "$1"
  done
}
...

Nice touch - I'm a bit of a RegEx fan, and considering we are already matching with one I'm inclined to extend it perhaps like this:

Code:

fetchip() {

    local IPDIGIT="(25[0-5]|2[0-4][0-9]|[1]?[0-9]?[0-9])"
    printf "%s: " "$1"
    until 
        read
        [[ "$REPLY" =~ ^(${IPDIGIT}\.){3}${IPDIGIT}$ ]]
    do
      printf "Invalid IP address - Please re-enter\n%s: " "$1"
    done

    printf -v $1 "%s" "$REPLY"
}

Quote:

Originally Posted by Arnaudh78

Thanks a lot, I have found a possible solution alone I know that isn't the best but It works

Yuck, repeating the same code 4 times. At least you realize this is bad LOL.

Last edited by Chubler_XL; 10-13-2016 at 06:45 PM..

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libbash

LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME

     libbash -- A bash shared libraries package.

DESCRIPTION

     libbash  is  a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
     want to load and use in scripts of your own.

     It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.

     Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1).  A bash shared library that can be  loaded
     using
     ldbash(1) must answer 4 requirments:

     1.     It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).

     2.     It must contain a line that begins with '#EXPORT='.  That line will contain (after the '=') a list of functions that the library
	    exports.  I.e. all the function that will be usable after loading that library will be listed in that line.

     3.     It must contain a line that begins with '#REQUIRE='.  That line will contain (after the '=') a list of bash libraries that are
	    required for our library.  I.e. every bash library that is in use in our bash library must be listed there.

     4.     The library must be listed (For more information, see ldbashconfig(8)).

   Basic guidelines for writing library of your own:
     1.     Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.

     2.     Try to declare all variables intended for internal use as local.

     3.     Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
		  __<library_name>_
	    For example, internal function myfoosort of hashstash library should be named as
		  __hashstash_myfoosort
	    This helps to avoid conflicts in global name space when using libraries that come from different vendors.

     4.     See html manual for full version of this guide.

AUTHORS

     Hai Zaar <haizaar@haizaar.com>
     Gil Ran <ril@ran4.net>

SEE ALSO

     ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1)

Linux								       Epoch								     Linux

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