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How to check exit status of unset variables

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# 1  
Old 02-02-2011
How to check exit status of unset variables
Hi All,

Is there any way to check exit status of unset variables?

In the following code PathX is not set and the script terminates without checking exit status.

Code:
#!/bin/bash

Path="/tmp/log"

cd ${PathX:?}

if [ $? -ne 0 ];then
   echo "Exit Status : non zero"
else
   echo "Exit Status : zero"
fi

Thanks in advance
# 2  
Old 02-02-2011
This code does not make sense to me. Rather than how you think it should be done, please explain what you want to accomplish.

To check if a variable is null or unset:
Code:
if [ ! -z "$var" ] ; then
  echo 'variable is defined'
else
  echo 'variable is not defined'
fi

Note: keep the quotes around the variable in the [ ] expression.
# 3  
Old 02-03-2011

A variable may have contents, be set but empty, or be unset:
Code:
if [ -n "$var" ]
then
  printf "Variable contains %s\n" "$var"
elif [ -n "${var+X}" ]
then
  printf "\$var is set but empty\n" 
else
  printf "\$var is not set\n"
fi


I use the following code in bash:
Code:
varstatus()
  if [ -n "${!1}" ]
  then
    printf "%s contains %s\n" "$1" "${!1}"
  elif [ -n "${!1+X}" ]
  then
    printf "%s is empty\n" "$1"
  else
    printf "%s is not set\n" "$1"
  fi

A sample run:
Code:
$ unset XYZ
$ varstatus XYZ
XYZ is not set
$ XYZ=
$ varstatus XYZ
XYZ is empty
$ XYZ=qwerty
$ varstatus XYZ
XYZ contains qwerty

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