possible gawk bug: 3.1.1 getline vs. 3.1.5 getline

[Alford, Seth]

Consider the following awk script:
----beginning of script----
#!/bin/sh

echo "from the regular file" > /tmp/regular
echo "input file line" > /tmp/input
awk ' BEGIN {
regular_basename="regular"
}
{
printf "Before getline, dollar 0 is:\n%s\n", $0 
printf "And the regular_basename is:\n%s\n", regular_basename
}
{
"ls -lsdk /tmp/"regular_basename" 2> /dev/null" | getline
printf "ls -lsdk /tmp/\"regular_basename\" 2> /dev/null | getline; and dollar 0 
is:\n%s\n", $0
close("ls -lsdk /tmp/"regular_basename" 2> /dev/null")
} ' /tmp/input
----end of script----

I have a system which is based on RedHat Linux 8.0 (RH8.0 rpm's
with a newer kernel.)  gawk --version says:

GNU Awk 3.1.1

I have another system based on CentOS 5.2.  gawk --version says:

GNU Awk 3.1.5

On gawk 3.1.1 on almost-RH 8.0, I get:

----start of cut and paste from RH 8.0 shell session----
address@hidden setha]# ./awktest
Before getline, dollar 0 is:
input file line
And the regular_basename is:
regular
ls -lsdk /tmp/"regular_basename" 2> /dev/null | getline; and dollar 0 is:
   4 -rw-r--r--    1 setha    se             22 Mar 31 15:31 /tmp/regular
address@hidden setha]# 
----end of cut and paste from RH 8.0 shell session----

On gawk 3.1.5 on almost-CentOS 5.2, I get:

----start of cut and paste from CentOS 5.2 shell session----
address@hidden tmp]# ./awktest
Before getline, dollar 0 is:
input file line
And the regular_basename is:
regular
ls -lsdk /tmp/"regular_basename" 2> /dev/null | getline; and dollar 0 is:
input file line
address@hidden tmp]# 
----end of cut and paste from CentOS 5.2 shell session----

The output is not the same.  I ran it as root in both cases, so I
don't think that permissions are a problem.  The later gawk
apparently does not like the 

        "... /tmp/"regular_basename

construct.  

A workaround is to construct the string that gets fed to getline,
separately:

----start of script with workaround---
#!/bin/sh

echo "from the regular file" > /tmp/regular
echo "input file line" > /tmp/input
awk ' BEGIN {
regular_basename="regular"
}
{
printf "Before getline, dollar 0 is:\n%s\n", $0 
printf "And the regular_basename is:\n%s\n", regular_basename
}
{
getline_string=sprintf("ls -lsdk /tmp/%s 2> /dev/null", regular_basename)

getline_string | getline
printf "getline_string piped into getline, ie:\n%s | getline\n", getline_string
printf "dollar 0:\n%s\n", $0
close(getline_string)
} ' /tmp/input
----end of workaround version of script----

This version works the same on both version of gawk.  Here's
the output:

----begin cut & paste----
address@hidden tmp]# ./awktest5
Before getline, dollar 0 is:
input file line
And the regular_basename is:
regular
getline_string piped into getline, ie:
ls -lsdk /tmp/regular 2> /dev/null | getline
dollar 0:
4 -rw-r--r-- 1 root root 1 Mar 31 16:11 /tmp/regular
address@hidden tmp]# 
----end of cut & paste----

I think that gawk 3.1.5 should run the script the way gawk 3.1.1
does, without the workaround.

--Seth


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