Bash to ash port, character-matching problem


 
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# 6  
Old 07-23-2014
A case statement will work in any Bourne type shell. This also makes it easy to test for an empty variable..
Code:
printf "Username: "
read _username
case $_username in 
  (*[![:alnum:]]*|"") 
    echo "invalid" ;;
  (*) 
    echo "valid"
esac

Note that will also allow letters with accents like é and ã
To exclude those, you could use (*[!a-zA-Z0-9]*|"") but that may not work properly because of a locale collation order...

--
Also note hat the proper negation character with character sets used in patterns is ! not ^ (even though it probably will work too)

Last edited by Scrutinizer; 07-23-2014 at 02:34 PM..
 
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SURFRAW-UPDATE-PATH(1)					User Contributed Perl Documentation				    SURFRAW-UPDATE-PATH(1)

NAME
surfraw-update-path - updates PATH in shell config files SYNOPSIS
surfraw-update-path [-add] [-remove] [-check] [-sys] [-all] [-help] [-shell=SHELL] DESCRIPTION
surfraw-update-path adds the surfraw elvi directory (/usr/lib/surfraw) to your PATH in your shell's config file. Currently it supports bash, sh, csh, tcsh, ash, dash, ksh, pdksh, zsh, rc, and es Don't forget to login again or source your login files for it to take effect. OPTIONS
-check Checks to see if the surfraw config code is present. This is the default. -add Adds the surfraw config code. -remove Removes the surfraw config code -sys Updates the system-wide shell config instead of the user. Must be done as root. -shell=SHELL Selects the shell to configure. Defaults to the value of the $SHELL environment variable. Currently supported shells are: sh, ash, bash, dash, csh, tcsh, ksh, pdksh, zsh, rc, and es. -all Attempts to configure the startup files for all known shells -help Gives a usage message RETURN VALUE
-check returns 0 if the surfraw code is present in the file, 1 if it is not found, or 2 on error. All other options return 0 on success, or 2 on error. ENVIRONMENT
SHELL Used to determine which shell to configure, if -shell is not given. HOME Used to find users config files. ENV Used by posix-compliant shells to specify a startup rc file. ZDOTDIR Used to find user config files for zsh. If not set, defaults to HOME. SEE ALSO
surfraw(1), sh(1), ash(1), bash(1), dash(1), csh(1), tcsh(1), ksh(1), pdksh(1), zsh(1), rc(1), es(1) AUTHOR
Ian Beckwith <ianb@erislabs.net> perl v5.12.4 2011-07-12 SURFRAW-UPDATE-PATH(1)