Quantifiers
Metacharacter + means one or more of the immediately-preceding item.
#!/bin/sh
: "Quantifiers:
Metacharacter + means one or more of the preceding item
Metacharacter * means any (none or more), which is similar to the ?
Notation {0,1} is the same as ?
When single number is given, such as [a-z]{3},
it matches exactly that many
"
A='<H1> <H2> <H3 > <H7>'
B='
<HR SIZE=14>
<HR SIZE = 14 >
<HRSIZE=14>
'
echo $A | grep '<H[1-6] *>' -o -E | tee result.txt
echo $B | grep '<HR +SIZE *= *[0-9]+ *>' -o -E | tee result.txt -a
<H1>
<H2>
<H3 >
<HR SIZE=14>
<HR SIZE = 14 >
More Examples
#!/bin/sh
: "Quantifiers:
Correct php variable names
Strings with double quotes
Time of the day, such as 9:17 AM
"
A='$a, $_b, $C, but not $1a'
B='"abc", but not "abc d'
C='
09:17 am
99:99 pm
9:17 am
12:30 pm
'
echo $A | grep '\$[a-zA-Z_][a-zA-Z_0-9]*' -o -E | tee res2.txt
echo $B | grep '"[^"]*"' -o -E | tee res2.txt -a
echo $C | grep '\<(1[012]|[1-9]):[0-5][0-9]\> (am|pm)' -o -E | tee res2.txt -a
$a
$_b
$C
"abc"
9:17 am
12:30 pm
Last update: 192 days ago
