how to use a command in sed s/match/replacement

Shell Programming and Scripting
1

hi,

how can i make use of a command in the replacement segment..

cat a | sed '/^[[:digit:]]\{3\}$/{
s/\(.\)/REPLACEMENT/g
}'

suppose if I want to use a awk command in the replacement section , how to achieve that ?

Thanks

2

Use backticks, double quotes and remove cat command (is useless):

sed "/^[[:digit:]*]\{3\}$/{
s/\(.*\)/`awk '{ blah blah blah }' awk_input_file.txt`/g
}" a

But I highly recommend to put the awk result into a variable and pass that variable in sed script, especially if the awk code is complex:

VAR=`awk '{ blah blah blah }' awk_input_file.txt`
sed "/^ ... $/s/.*/${VAR}/g" sed_input_file.txt