check dynamic variable name exist in bash

Question

I wish got message "missing global variable varB".

 chk_var() {
   local n v
   for n in varA varB varC; do
     eval v=\$$n test -n "$v" && [[ -n $v ]] \
       || echo "Err: missing global variable \$$n"
   done
 }
varA=3
varB=4
chk_var

Community · Accepted Answer · 2017-05-23 12:21:49Z

9

chk_var() {
   local n v 
   for n in varA varB varC; do
       if [ -z ${!n+x} ]; then 
           echo "$n is unset"; 
       else 
           echo "$n is set to '${!n}'"; 
       fi
   done
 }
varA=3
varB=4
chk_var

see: How to check if a variable is set in Bash?

the ! before n in ${!n+x} and ${!n} is for indirect access.

Gives:

varA is set to '3'
varB is set to '4'
varC is unset

edited May 23, 2017 at 12:21

CommunityBot

11 silver badge

answered May 13, 2015 at 4:12

perreal

98.7k23 gold badges159 silver badges187 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

check dynamic variable name exist in bash

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related