Unclear on the Concept

A list of true-life Programming and Sysadmin FAILs

(Identifying data is obscured to protect the clueless.)

2011-11-09: You're Doing it Wrong

From an email message after someone traced data flow:

"There is a PL/SQL package in $DATABASE that this CGI script calls indirectly (CGI script executes ssh, which in turn executes sqlplus on $DATABASE_HOST, which in turn executes $SQLSCRIPT.sql script which in turn calls $STORED_PROCEDURE_NAME procedure)."

2011-07-12: I will call my function "push"

I just spent far too long diving through far too many perl scripts that use functions from a "Pushpull.pm" module. One of which is called pull. So to avoid colliding with the built-in pull, you have to call it by &pull(...). Now I understand why all that code looked like it was from the Perl 4 era....

Kill. Me. Now.

2011-01-28: loop? what loop? what loop? what loop? what loop? what loop? what loop? ...

% ls -l /etc/logcheck/ignore.d.server/exim
lrwxrwxrwx    1 root     logcheck       23 Jan 28 06:04 /etc/logcheck/ignore.d.server/exim -> ../ignore.d.server/exim

2011-01-24: Bad DNS (BAD!)

This stupidity is not our company; our email servers can't send email to them for some reason:

% host example.com
example.com is an alias for example.com.
example.com is an alias for example.com.
example.com is an alias for example.com.

(No, the domain in question was not actually example.com.)

2010-07-19: useless lock file

I found a script today that has a lock file, which is only referenced when creating it and removing it. They even have special code to remove it when it gets a SIGINT. But nothing actually tests for its existence.

$lock_file   = "/path/to/lockfile";

$SIG{'INT'}  = 'INT_handler';

...snip...

#-- Create lock file before processing

`touch $lock_file`;

...snip...

#--Remove Lock file after processing

unlink $lock_file;
exit(0);

sub INT_handler {

        print  STDERR "Program Interrupted\n";

        if( -f $lock_file) {
                unlink $lock_file;
        }
        exit(-2);

}

2010-06-02: useless tee

Found in a shell script, repeated a bunch of times:

echo "Error: code $? when transfering $FILE, skip" |tee|logger -t $tag -p $priority

tee without any arguments simply copies its standard input to its standard output: it's basically cat here, which is useless.

2010-04-20

Found in a perl script:

my $end_time         = `perl -e '{print time(), "\n"}'`;

2010-03-18

This isn't really an "unclear on the concept" — it's just very funny.

-----Original Message-----
From: Cron Daemon [mailto:root@HOST]
Sent: Thursday, March 18, 2010 16:31
To: root@HOST
Subject: Cron <root@HOST> [ -x /usr/local/sbin/SCRIPT ] &&  /usr/local/sbin/SCRIPT 2>&1

/var/log/faillog: No such file or directory

2010-03-12

This is from old monitoring code. Server is a socket. $timeout = 5. I found this when trying to figure out why this always paused for an extra 5 seconds. I include my fix as a hint as to why this is dumb.

-    while (select($socketvecout=$socketvec, undef, undef, $timeout) ) {
+    if (select($socketvecout=$socketvec, undef, undef, $timeout)) {
         recv(Server, $server_reply, 1500, 0)
             or die "udp recv failed testing $port: $!\n";
     }
+    else {
+        return "timed out waiting for response from $daemon on port $port";
+    }

2010-03-02

Today I ran across a script with two fun examples.

First example:

DATE=`perl -e '@arr = localtime(time - 86400); printf "%04d:%02d:%02d", $arr[5]+1900, $arr[4]+1, $arr[3];'`

YEAR=`echo $DATE | cut -d: -f1`
MONTH=`echo $DATE | cut -d: -f2`
DAY=`echo $DATE | cut -d: -f3`

This one is not totally insane, just ugly and inefficient. There are a number of ways to fix it, including a single 'eval' line:

eval `perl -e '@arr = localtime(time - 86400); printf "YEAR=%04d; MONTH=%02d ; DAY=%02d", $arr[5]+1900, $arr[4]+1, $arr[3];'`

What's interesting is that they only need $YEAR, $MONTH, and $DAY separate because of the other example from this script:

if [ ! -d $ARCHIVE_DIR/$YEAR ]
then
        mkdir -p $ARCHIVE_DIR/$YEAR
fi

if [ ! -d $ARCHIVE_DIR/$YEAR/$MONTH ]
then
        mkdir -p $ARCHIVE_DIR/$YEAR/$MONTH
fi

if [ ! -d $ARCHIVE_DIR/$YEAR/$MONTH/$DAY ]
then
        mkdir -p $ARCHIVE_DIR/$YEAR/$MONTH/$DAY
fi

'mkdir -p' already makes any missing parent directories, and doesn't make (nor throw an error for) any directory that already exists), so this can be collapsed to

mkdir -p $ARCHIVE_DIR/$YEAR/$MONTH/$DAY

And thus both examples could be collapsed to two lines:

YMD=`perl -e '@arr = localtime(time - 86400); printf "%04d/%02d/%02d", $arr[5]+1900, $arr[4]+1, $arr[3];'`
mkdir -p $ARCHIVE_DIR/$YMD

and then from then on, $YMD could be used (because the script refers only to $YEAR/$MONTH/$DAY [combined] from then on).

2009-12-22

What, you mean Perl's print doesn't convert strftime() conversion specifiers for you automatically?

print $sendmail_fh "Date: %a, %d %b %Y %T %Z\n";

(This is printing to a pipe connected to the standard input of /usr/lib/sendmail -t. This is also my own error. Sigh.)

2009-10-01

% ps -ef | grep "[t]ail"
clueless 25624   924   0   Jul 17 ?   0:00 tcsh -c tail -f /path/to/logfile | tail -3
clueless 25660 25624   0   Jul 17 ?   5:07 tail -f /path/to/logfile
clueless 25661 25624   0   Jul 17 ?   0:03 tail -3

2009-09-22

I came across a perl script today that was entirely made up of

system("shell-command1 ARGS1");

system("shell-command2 ARGS2");

system("shell-command3 ARGS3");

and so on. Sigh.

2009-08-28

sub getHashCount($){
  my $count = 0;
  for my $k (keys %{$_[0]}){
    $count++;
  }
  return $count;
}

(As opposed to simply using

scalar(keys %hash)

2009-08-27

% head -6 /path/to/logroll/script
# daemon's agelogs script
#
#!/bin/sh

# $Source: /path/to/cvs/repository/for/logroll/script,v $
# $Id: script,v 1.4 2008/03/11 17:38:35 clueless Exp $
%

It's a darn good thing that /bin/sh is the default shell.