open(F1,"+>>$FILE") works on Solaris,AIX but not Linux??

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

The following snippet is to set a variable to "PASSED" unless the word "FAILED" appears in a file. This works fine on AIX and Solaris but on Linux Redhat 7.3, the @result_array is empty, resulting in the grep returning 0 (count of FAILED) and thus reports a "PASSED" instead of a "FAILED" :-(

#!/usr/local/it/bin/perl -w

#
# Create sample file with two 
# instances of "FAILED" string
#

$RFILE="example_file";                                      
open(F1,">$RFILE") or die "cannot open $RFILE for creation!\n";
print F1 "FAILED\nPASSED\nPASSED\nFAILED\nPASSED\n";              
close(F1);

#
# Open file for Append AND read
#
open(RESULT,"+>>$RFILE") or die "cannot open $RFILE\n";

#
# Set an array to the filehandle and count the
#  number of lines with the "FAILED" string
#

my @result_array = <RESULT>;
$number_failures = grep /FAILED/, @result_array;

#
# Overall status is FAILED if any "FAILED" strings
# are found
#

$OVERALL_STATUS = ($number_failures > 0) ? "FAILED":"PASSED";
print "+-------------------+\n";
print "|                   |\n";
print "| EO_FAIL_03 $OVERALL_STATUS |\n";
print "|                   |\n";
print "+-------------------+\n";
close(RESULT);
[download]

If I change the open line to:

open(RESULT,"$RFILE")
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it works fine! And yes...I do need it to be "+>>" for other operations not shown in this snippet. Any insight on this would be real helpful.

Comment on open(F1,"+>>$FILE") works on Solaris,AIX but not Linux?? Select or Download Code

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Re: open(F1,"+>>$FILE") works on Solaris,AIX but not Linux?? by pfaut (Priest) on Feb 24, 2003 at 21:59 UTC
An open with mode '>>' should position to end of file. You need to seek to the beginning in order to read from the file. I added two lines to your program and it now appears to work as you would like it to. #!/usr/local/it/bin/perl -w # # Create sample file with two # instances of "FAILED" string # use Fcntl qw(SEEK_SET); $RFILE="example_file"; open(F1,">$RFILE") or die "cannot open $RFILE for creation!\n"; print F1 "FAILED\nPASSED\nPASSED\nFAILED\nPASSED\n"; close(F1); # # Open file for Append AND read # open(RESULT,"+>>$RFILE") or die "cannot open $RFILE\n"; seek RESULT,0,SEEK_SET; # # Set an array to the filehandle and count the # number of lines with the "FAILED" string # my @result_array = <RESULT>; $number_failures = grep /FAILED/, @result_array; # # Overall status is FAILED if any "FAILED" strings # are found # $OVERALL_STATUS = ($number_failures > 0) ? "FAILED":"PASSED"; print "+-------------------+\n"; print "\| \|\n"; print "\| EO_FAIL_03 $OVERALL_STATUS \|\n"; print "\| \|\n"; print "+-------------------+\n"; close(RESULT); <code>--- print map { my ($m)=1<<hex($_)&11?' ':''; $m.=substr('AHJPacehklnorstu',hex($_),1) } split //,'2fde0abe76c36c914586c'; [download]	[reply] [d/l]
Re: open(F1,"+>>$FILE") works on Solaris,AIX but not Linux?? by jasonk (Parson) on Feb 24, 2003 at 21:58 UTC
I don't have a Solaris or AIX machine to check, but the Linux man page for fopen says that r+ (+<) and w+ (+>) open the file and position the stream at the beginning of the file, while a+ (+>>) positions the stream at the end of the file. So your options are either to open with +>> and then seek to the beginning of the file before reading, or open with +<, read, and then seek to the end of the file before writing (although you will probably end up at the end of the file anyway, if you read the entire contents).	[reply]
Re: open(F1,"+>>$FILE") works on Solaris,AIX but not Linux?? by runrig (Abbot) on Feb 24, 2003 at 22:00 UTC
'+>>' is not listed in the open docs, so I wouldn't use it as a supported option. I don't see why you couldn't use '+<', as that is listed in the docs. After opening the file, you can read from it, and/or seek to the end of the file for appending. Update: I take it back, I do see '+>>' in the docs, but you would then need to use seek to read from the beginning of the file, as already suggested.	[reply]