Processing bash variable with sed
SiegeX's answer is better for this particular case, but you should also know how to pass arbitrary text to sed
.
sed
is expecting filenames as its second, third, etc. parameters, and if it doesn't find any filenames, it reads from its standard input. So if you have text that you want to process that's not in a file, you have to pipe it to sed
. The most straightforward way is this:
echo "blah blah" | sed 's/blah/blam/g'
So your example would become:
LAT=$(echo "$LATLNG" | sed 's/(\(.*\),\(.*\))/\1/g')
LON=$(echo "$LATLNG" | sed 's/(\(.*\),\(.*\))/\2/g')
Alternate (better but more obscure) Methods
If you think there's any chance that $LATLNG
could begin with a dash, or if you want to be pedantic, you should use printf
instead of echo
:
printf '%s' "$LATLNG" | sed 's/foo/bar/g'
Or a "here document", but that can be a little awkward with the construct you're using:
LAT=$(sed 's/foo/bar/g' <<END
$LATLNG
END
)
Or if you're using bash
and not worried about portability, you can use a "here string":
sed 's/foo/bar/g' <<< "$LATLNG"
This can be solved via pure shell syntax. It does require a temp variable because of the parentheses (brackets) though:
#!/bin/bash
LATLNG="(53.3096,-6.28396)"
tmp=${LATLNG//[()]/}
LAT=${tmp%,*}
LNG=${tmp#*,}
Alternatively, you can do it in one go by playing with IFS
and using the read
builtin:
#!/bin/bash
LATLNG="(53.3096,-6.28396)"
IFS='( ,)' read _ LAT LNG _ <<<"$LATLNG"
Here's a solution that will work in any POSIX shell:
parse_coordinates () {
IFS='(), ' # Use these characters as word separators
set -f # Disable globbing
set $1 # Split $1 into separate words
set +f # Restore shell state
unset IFS
LAT=$2 # $1 is the empty word before the open parenthesis
LON=$3
}
parse_coordinates "$LATLNG"
Here's another equally portable solution that parses the specific syntax used.
LAT=${LATLNG%\)} # strip final parenthesis
LAT=${LAT#\(} # strip initial parenthesis
LON=${LAT##*[, ]} # set LON to everything after the last comma or space
LAT=${LAT%%[, ]*} # set LAT to everything before the first comma or space