gawk: Getline/Variable/Coprocess
4.10.8 Using 'getline' into a Variable from a Coprocess
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When you use 'COMMAND |& getline VAR', the output from the coprocess
COMMAND is sent through a two-way pipe to 'getline' and into the
variable VAR.
In this version of 'getline', none of the predefined variables are
changed and the record is not split into fields. The only variable
changed is VAR. However, 'RT' is set.
Coprocesses are an advanced feature. They are discussed here only
because this is the minor node on 'getline'. Two-way I/O, where
coprocesses are discussed in more detail.