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Called program - stdin/stdout

In Unix the verb defined below calls a program, writes to its standard input, and reads its output. 
run=: 4 : 0
'p o i'=. 2!:2 x    NB. Run command, save Process, Output, Input
y fwrite i          NB. Write to its input
fclose i            NB. Close its input
2!:3 p              NB. Wait for process to terminate
z=.fread o          NB. Read its output
fclose o            NB. Close its output
z                   NB. Result
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