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check numeric value entered
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Original Message
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Name: cf0sro
Date: April 24, 2003 at 13:06:10 Pacific
Subject: check numeric value entered
OS: redhat 7.3
CPU/Ram: pIII 512MByte
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Comment: how do I check if a variable contains a numeric value before trying to perform a calculation on it.
The variable is read in from the keyboard by a shell script
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Response Number 1
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Name: nails
Date: April 24, 2003 at 13:30:26 Pacific
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Reply: (edit)
# this function sets the exit to non zero if $1 non numeric
is_digit () {
expr "$1" + 1 > /dev/null 2>&1
}
# all on one line
is_digit $1 || { echo "$1 is non-numeric" && exit 1; } Regards, Nails
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