Display TAB in Shell Script

Hi cutie,

I found one reference to this issue, and it seems that "\t" works.  But it may require certain conditions that aren't obvious.

  http://www.webservertalk.com/archive286-2005-11-1306144.html
  http://archives.devshed.com/forums/databases-139/loading-tab-delimited-text-file-using-fastload-teradata-1609484.html
 

The links are to the same thread.


Kent

can you hardcode the tab like
TAB="    "

The problem is that you are passing the value of your delimiter to an input (<<) statement, as part of your database statement. The string passed via (<<) is being sent literally, as you have typed it.

So, in your example, the value of "${TAB}" is expanded literally, so that you are actually passing "\t" as the delimiter, and not a tab character as you expect.

You say you would like to do this in case the delimiter changes in a later iteration, which is commendable when you are writing a generic script, but since your script uses 'drop table', which is an aggressive and job-specific task, I wouldn't bother trying to genericise the script, just type the tab in place.

If you really want a generic script, you should at least:

1) Move the database instructions to an external file, passed to the script either as stdin, or as a named file parameter, or as an editable constant like you have with TAB

2) Instead of varying the value you pass to SET RECORD VARTEXT, you should always use the same delimiter, and instead pass the input file through a sed command to bring it into the format required by the script, by replacing the delimiter for that file with the delimiter enforced by the script.

However, if you insist on doing it this way, pretending to have a generic script, you can achieve this in a number of ways:

A) By breaking down the "<<" statement into three steps:

#step 1
fastload << EOT1
${LOGON}
DROP TABLE ${DATABASE}.${TABLE}_Err1;
DROP TABLE ${DATABASE}.${TABLE}_Err2;
ERRLIMIT 50;

BEGIN LOADING
${DATABASE}.${TABLE}
   ERRORFILES ${DATABASE}.${TABLE}_Err1,
              ${DATABASE}.${TABLE}_Err2
   CHECKPOINT 100000;

SET RECORD VARTEXT
EOT1

# step 2
fastload << $TAB

# step 3
fastload << EOT2
;
DEFINE
     Col1       (VARCHAR(5))
     ,col2     (VARCHAR(2))
     ,col3      (VARCHAR(12))

EOT2


B) By removing the quotes.  Note that the syntax ${..} implies a quote itself, so you are essentially passing ""\t"".  Anyway, just try replacing "${TAB}" with $TAB and see if that works.  If it doesn't, you need to split the << input so that the TAB is passed outside of any other string.

When the shell invokes your command, it will expand any tab character as whitespace, unless that whitespace is quoted.  Therefore, there is no other way of passing your tab as a command-line parameter unless it is quoted.

Even quoted tabs may not pass correctly depending on your prevailing shell and version of UNIX, although in this instance, you should be safe since you are using the core bourne shell.

However, please let me say again that you are approaching this the wrong way around.  You are going to the trouble of creating a 'generic' script, by concerning yourself with the tab character, while the script includes code which is job-specific.

If you genuinely have input files that might be delimited by one of many characters, why dont you make the first job in your script to format the input file into a standard delimited file and *then* pass it to your database job.  So, if the file is delimited by spaces, or commas, replace these with tabs into a temporary file, then work with that file instead.

Furthermore, there is probably a limited number of possible delimiters that could be used depending on your data, and there is probably a known architecture to the input file, so for example it may be possible to work out that the delimiter character is always the sixth character in the file.