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Old 05-03-2007
hitmansilentass hitmansilentass is offline
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Quote:
Originally Posted by cfajohnson

To exit the script if any var is empty or unset:

Code:
: ${XXXX:?} ${YYYYY:?} ${TTTT:?} ${NNNN:?} ${QQQQ:?}
To execute something if any parameter is empty or unset:

Code:
var=${XXXX:+A}${YYYYY:+A}${TTTT:+A}${NNNN:+A}${QQQQ:+A}
if [ ${#var} -ne 5 ]; then
THis is exactly what i was looking for. could you explain this please???
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Old 05-03-2007
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cfajohnson cfajohnson is offline Forum Advisor  
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Join Date: Mar 2007
Location: Toronto, Canada
Posts: 2,361
Quote:
Originally Posted by hitmansilentass
THis is exactly what i was looking for. could you explain this please???


First example:

: -- a command that does nothing but evaluate its arguments.

${XXXX:?} -- Bourne-shell parameter expansion; exits with an error if the variable is unset or empty.

${YYYYY:?} ${TTTT:?} ${NNNN:?} ${QQQQ:?} -- Ditto
Second example:

[b]${XXXX:+A} -- Bourne-shell parameter expansion that replaces the variable with A if it is set and not null.

var -- will contain AAAAA (i.e., have a length of 5) if all the variables are set and not null. If any are unset or null, the length of $var will be less than 5.

${#var} -- POSIX parameter expansion that gives the number of characters in the variable.
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