Info Catalog gawk: Getline/Pipe gawk: Getline gawk: Getline/Coprocess

gawk: Getline/Variable/Pipe

 
 4.10.6 Using 'getline' into a Variable from a Pipe
 --------------------------------------------------
 
 When you use 'COMMAND | getline VAR', the output of COMMAND is sent
 through a pipe to 'getline' and into the variable VAR.  For example, the
 following program reads the current date and time into the variable
 'current_time', using the 'date' utility, and then prints it:
 
      BEGIN {
           "date" | getline current_time
           close("date")
           print "Report printed on " current_time
      }
 
    In this version of 'getline', none of the predefined variables are
 changed and the record is not split into fields.  However, 'RT' is set.
 
    According to POSIX, 'EXPRESSION | getline VAR' is ambiguous if
 EXPRESSION contains unparenthesized operators other than '$'; for
 example, '"echo " "date" | getline VAR' is ambiguous because the
 concatenation operator is not parenthesized.  You should write it as
 '("echo " "date") | getline VAR' if you want your program to be portable
 to other 'awk' implementations.
 

Info Catalog gawk: Getline/Pipe gawk: Getline gawk: Getline/Coprocess