How to unset all variables in shell?

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# 1  
Old 10-01-2009
How to unset all variables in shell?

can I use unset to unset all the variables in a shell sciprt?


whether this unset will afftect any system variables?

# 2  
Old 10-01-2009
The unset command deletes a shell variable,or non-shell variable effectively setting it to null. Note that this command
does not affect positional parameters

but note that you need to put the variable name after the unset command.

unset PATH
echo $PATH

variable=hello # Initialized.
echo "variable = $variable"
unset variable # Unset.
# Same effect as: variable=
echo "(unset) variable = $variable" # $variable is null.

# 3  
Old 10-01-2009
The following function 'gsunset', deletes the variables specified by an RE :
  local var_re="${1:-.*}"
  eval $( set | \
         awk -v FS='='        \
             -v VAR="$var_re" \
            '$1 ~ VAR { print "unset", $1 }' )


echo "Vars before gunset"
set | grep ^VAR
gunset 'VAR.*'
echo "Vars after gunset"
set | grep ^VAR

Vars before gunset
Vars after gunset

# 4  
Old 10-01-2009
Change your approach. NEVER use undeclared variables. There is an option "set -o nounset" if I remember correctly.
You should have something like this:

#!/bin/env ksh
typeset my_variable
typeset all_my_variables_should_be_defined_like_that

Last edited by vgersh99; 10-01-2009 at 05:48 PM.. Reason: code tags, PLEASE!
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