Transforming text with 'sed' or 'awk' -

i have large input set looks this:

label: foo, other text: text description...    <insert label> item: item description...    <insert label> item: item description... label: bar, other text:...    <insert label> item:... label: baz, other text:...    <insert label> item:...    <insert label> item:...    <insert label> item:... ... 

i'd transform pull out label name (e.g. "foo") , replace tag "<insert label>" on following lines actual label.

label: foo, other text: text description...    foo item: item description...    foo item: item description... label: bar, other text:...    bar item:... label: baz, other text:...    baz item:...    baz item:...    baz item:... ... 

can done sed or awk or other unix tool? if so, how might it?

one solution using sed:

content of script.sed:

## when line beginning 'label' string. /^label/ {     ## save content 'hold space'.     h         ## string after label (removing other characters)     s/^[^ ]*\([^,]*\).*$/\1/      ## save in 'hold space' , original content     ## of line (exchange contents).     x         ## print , read next line.     b    } ###--- commented wrong behaviour ---###     #--- g #--- s/<[^>]*>\(.*\)\n\(.*\)$/\2\1/  ###--- , fixed ---### ## when line begins '<insert label>' /<insert label>/ {     ## append label name line.     g         ## , substitute '<insert label>' string it.     s/<insert label>\(.*\)\n\(.*\)$/\2\1/ } 

content of infile:

label: foo, other text: text description...    <insert label> item: item description...    <insert label> item: item description... label: bar, other text:...    <insert label> item:... label: baz, other text:...    <insert label> item:...    <insert label> item:...    <insert label> item:... 

run like:

sed -f script.sed infile 

and result:

label: foo, other text: text description...     foo item: item description...     foo item: item description... label: bar, other text:...     bar item:... label: baz, other text:...     baz item:...     baz item:...     baz item:...