Sed to reverse two words

Question

echo "AXIS2C_HOME=/usr/local/Axis2C" | sed 's/(^AXIS2C_HOME=) (.*)/ \2 \1/'

The output i am expecting is /usr/local/Axis2C AXIS2C_HOME=

I cant figure out what i am doing wrong :(

Answer 1

The trivial answer is "more backslashes, less spaces":

echo "AXIS2C_HOME=/usr/local/Axis2C" | sed 's/\(^AXIS2C_HOME=\)\(.*\)/\2 \1/'

But the broader answer is, "wait, what are you trying to do?" Do you want the key-value pairs to be split into useful variables, or are you really just trying to munge the input into the reverse syntax in order t feed it to something else?

Answer 2

You have an erroneous space after the =. Try:

sed 's/\(^AXIS2C_HOME=\)\(.*\)/\2 \1/'

The following also works and is a bit shorter. \1 will be anything before the first /

sed 's|^\([^/]*\)\(/.*\)|\2 \1|'

Answer 3

Sed is great, but Perl can do this too, and it doesn't require the forest of backslashes:

% echo "AXIS2C_HOME=/usr/local/Axis2C" | perl -pe 's/(^AXIS2C_HOME=)(.*)/\2 \1/'
/usr/local/Axis2C AXIS2C_HOME=

Plus, you've got the full power of the regular expression engine, so you can do even more complex patterns.