What exactly does the following do?
MY_VAR=${MY_INPUT##*$'\n'}
Deletes the longest match of the substring *\n from the start of the string stored in MY_INPUT. Note that * is a wildcard, so the result is that every line of MY_INPUT is discarded except the last one, which is stored in MY_VAR. The $ before '\n' is put there just to evaluate \n and consider it as a newline instead of literally the characters \ and n.
Some examples:
MY_INPUT MY_VAR
"a\nb\nc" -> "c"
"a\n" -> ""
"abcde\n\n\ndef" -> "def"
Note: in the second example the last line is empty so MY_VAR is an empty string.
As requested, another way to do this could be:
tail -n1 <<< "$MY_INPUT"
or:
echo "$MY_INPUT" | tail -n1
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@Jim
MY_INPUT=$( printf 'line1\nline2\nline3' ); MY_VAR=${MY_INPUT##*$'\n'}; echo "$MY_VAR"will outputline3. It's basically doingtail -n 1on the contents of$MY_INPUT. – Kusalananda♦ Mar 21 '18 at 11:52 -
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