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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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME

     atf-sh [-s shell] -- interpreter for shell-based test programs

SYNOPSIS

     atf-sh script

DESCRIPTION

     atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library.

     atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL.  atf-sh executes the inter-
     preter, loads the atf-sh(3) library and then runs the script.  You must consider atf-sh to be a POSIX shell by default and thus should not
     use any non-standard extensions.

     The following options are available:

     -s shell	  Specifies the shell to use instead of the value provided by ATF_SHELL.

ENVIRONMENT

     ATF_LIBEXECDIR    Overrides the builtin directory where atf-sh is located.  Should not be overridden other than for testing purposes.
     ATF_PKGDATADIR    Overrides the builtin directory where libatf-sh.subr is located.  Should not be overridden other than for testing purposes.
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EXAMPLES

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	   #! /usr/bin/env atf-sh

     Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh.  Instead, you have to hardcode
     the path to atf-sh in the script and then use the -s option afterwards as a single parameter:

	   #! /path/to/bin/atf-sh -s/bin/bash

ENVIRONMENT

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SEE ALSO

     atf-sh(3)

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