What are ':a' and 'ta' in sed?

What are :a开发者_如何转开发 and ta in sed?

Example:

sed -e :a -e '/\\$/N; s/\\\n//; ta'

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t label is testing, which goes to label (in your case label is "a") is substitute was performed.

:a and ta are pair. ":a" fist makes a lable . if the sequence is completed before lable "ta"，goto ":a" keep executing.Just like the loop.