gawk: Retrying Input
4.12 Retrying Reads After Certain Input Errors
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This minor node describes a feature that is specific to 'gawk'.
When 'gawk' encounters an error while reading input, by default
'getline' returns -1, and subsequent attempts to read from that file
result in an end-of-file indication. However, you may optionally
instruct 'gawk' to allow I/O to be retried when certain errors are
Auto-set::):
PROCINFO["INPUT_NAME", "RETRY"] = 1
When this element exists, 'gawk' checks the value of the system (C
language) 'errno' variable when an I/O error occurs. If 'errno'
indicates a subsequent I/O attempt may succeed, 'getline' instead
returns -2 and further calls to 'getline' may succeed. This applies to
the 'errno' values 'EAGAIN', 'EWOULDBLOCK', 'EINTR', or 'ETIMEDOUT'.
This feature is useful in conjunction with 'PROCINFO["INPUT_NAME",
"READ_TIMEOUT"]' or situations where a file descriptor has been
configured to behave in a non-blocking fashion.