Replacing the last word of a path using sed.

Question

I have the following: param="/var/tmp/test" I need to replace the word test with another word such as new_test

need a smart way to replace the last word after "/" with sed

Answer 1

echo 'param="/var/tmp/test"' | sed 's/\/[^\/]*"/\/REPLACEMENT"/'
param="/var/tmp/REPLACEMENT"

echo '/var/tmp/test' | sed 's/\/[^\/]*$/\/REPLACEMENT/' 
/var/tmp/REPLACEMENT

Answer 2

You don't need sed for this...basename and dirname are a better choice for assembling or disassembling pathnames. All those escape characters give me a headache....

param="/var/tmp/test"
param_repl=`dirname $param`/newtest

Answer 3

Extracting bits and pieces with sed is a bit messy (as Jim Lewis says, use basename and dirname if you can) but at least you don't need a plethora of backslashes to do it if you are going the sed route since you can use the fact that the delimiter character is selectable (I like to use ! when / is too awkward, but it's arbitrary):

$ echo 'param="/var/tmp/test"' | sed ' s!/[^/"]*"!/new_test"! '
param="/var/tmp/new_test"

We can also extract just the part that was substituted, though this is easier with two substitutions in the sed control script:

$ echo 'param="/var/tmp/test"' | sed ' s!.*/!! ; s/"$// '
test

Answer 4

It's not clear whether param is part of the string that you need processed or it's the variable that holds the string. Assuming the latter, you can do this using only Bash (you don't say which shell you're using):

shopt -s extglob
param="/var/tmp/test"
param="${param/%\/*([^\/])//new_test}"

If param= is part of the string:

shopt -s extglob
string='param="/var/tmp/test"'
string="${string/%\/*([^\/])\"//new}"