Bug with gawk regex interval processing

[Mike Kistler]

Hello,

I think I have uncovered a bug in gawk regular expression interval
processing.  Below is a script to reproduce the problem.

#!/bin/bash

# This script reproduces an apparent bug in regex processing in awk.
# The problem is that interval expressions are not handled properly.

# This problem occurs on RedHat 8.0.  awk is packages in gawk-3.1.1-4

# The purpose of the awk script is to eliminate the first three space-delimited 
fields from each
# input record and print the remaining contents.

cat > /tmp/awkbug.dat <<EOF
 token1  token2   token3   token4
 token1  token2   token3   token4  token5
 token1  token2   token3   token4  token5 token6
 token   token    token    token4
 token   token    token    token4  token5 token6
EOF

# This awk script fails ... apparently because of the interval.
awk --posix '{sub(/^[ ]*([^ ]+[ ]+){3}/, "", $0); print $0}' /tmp/awkbug.dat

# This awk script succeeds, but is equivalent to the one that fails.
awk --posix '{sub(/^[ ]*([^ ]+[ ]+)([^ ]+[ ]+)([^ ]+[ ]+)/, "", $0); print $0}' 
/tmp/awkbug.dat


Mike Kistler