I am thinking of using sed for reading .properties file, but was wondering if there is a smarter way to do that from bash script?
The solutions mentioned above will work for the basics. I don't think they cover multi-line values though. Here is an awk program that will parse Java properties from stdin and produce shell environment variables to stdout:
BEGIN {
FS="=";
print "# BEGIN";
n="";
v="";
c=0; # Not a line continuation.
}
/^\#/ { # The line is a comment. Breaks line continuation.
c=0;
next;
}
/\\$/ && (c==0) && (NF>=2) { # Name value pair with a line continuation...
e=index($0,"=");
n=substr($0,1,e-1);
v=substr($0,e+1,length($0) - e - 1); # Trim off the backslash.
c=1; # Line continuation mode.
next;
}
/^[^\\]+\\$/ && (c==1) { # Line continuation. Accumulate the value.
v= "" v substr($0,1,length($0)-1);
next;
}
((c==1) || (NF>=2)) && !/^[^\\]+\\$/ { # End of line continuation, or a single line name/value pair
if (c==0) { # Single line name/value pair
e=index($0,"=");
n=substr($0,1,e-1);
v=substr($0,e+1,length($0) - e);
} else { # Line continuation mode - last line of the value.
c=0; # Turn off line continuation mode.
v= "" v $0;
}
# Make sure the name is a legal shell variable name
gsub(/[^A-Za-z0-9_]/,"_",n);
# Remove newlines from the value.
gsub(/[\n\r]/,"",v);
print n "=\"" v "\"";
n = "";
v = "";
}
END {
print "# END";
}
As you can see, multi-line values make things more complex. To see the values of the properties in shell, just source in the output:
cat myproperties.properties | awk -f readproperties.awk > temp.sh
source temp.sh
The variables will have '_' in the place of '.', so the property some.property will be some_property in shell.
If you have ANT properties files that have property interpolation (e.g. '${foo.bar}') then I recommend using Groovy with AntBuilder.
Here is my wiki page on this very topic.
This would probably be the easiest way: grep + cut
# Usage: get_property FILE KEY
function get_property
{
grep "^$2=" "$1" | cut -d'=' -f2
}