CODEWITHSUNDEEP
bashshell
yPhil
yPhil

Reputation: 8367

BASH Wild-card : Select all variables (not the content)

I have a bunch of variables that I want to check, and if they contain the value "None" then I want to empty them.

    var1=(check for some value, sometimes it returns "none")
    var2=(check for some value, sometimes it returns "none")
    var3=(check for some value, sometimes it returns "none")
    someBizzareName=(check for some value, sometimes it returns "none")

    if [[ "${var1}" == "None" ]] ; then
        var1=""
    fi
    if [[ "${var2}" == "None" ]] ; then
        var2=""
    fi

And this is all working fine and dandy, only since I have a lot of varN, I will end up with a ton of if [[ "${varN}" == "None" ]] and I have to know their names ; so I was wondering, since it's in BASH very nature to search and match everything, if there is a wild-card for variables, inside a for loop, that will match all vars, something like ${*} (I tried that, does'nt work) ? I have done all kinds of searches but always find something about matching variable content, not the var itself..?

Upvotes: 5

Views: 4486

Answers (3)

jim
jim

Reputation: 21

You may also use the builtin compgen:

man bash | less -p 'compgen .option. .word.'
compgen -A variable B

Upvotes: 2

shellter
shellter

Reputation: 37288

All, yes ;-)

Most Unix/Linux support either the env or printenv which produce output like

 var=value

The export command, without arguments, will list all exported variables in your environment. 

for varAndVal in $( env ) ; do
   case ${varAndVal} in
     *=none ) 
      eval \$${varAndVal}=
      #OR eval unset \$${varAndVal}
     ;;
    esac
 done

I hope this helps.

P.S. as you appear to be a new user, if you get an answer that helps you please remember to mark it as accepted, and/or give it a + (or -) as a useful answer.

Upvotes: 1

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 798744

All, no. But you can match a pattern (but not *).

$ echo "${!B*}"
BASH BASHOPTS BASHPID BASH_ALIASES BASH_ARGC BASH_ARGV BASH_CMDS BASH_COMMAND BASH_LINENO BASH_SOURCE BASH_SUBSHELL BASH_VERSINFO BASH_VERSION

Upvotes: 8

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