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Full Discussion: Update file record inside read loop
Top Forums Shell Programming and Scripting Update file record inside read loop Post 302742631 by Corona688 on Tuesday 11th of December 2012 11:03:09 AM
Old 12-11-2012
Not really, no. There is no seamless 'insert' operation for a file. To add extra data to the middle of a file, you must rewrite all the data that comes after it. That is why inserting data is so complicated, you never really do so.

The usual solutions for doing it all in one step, ed or sed -i, still use a temp file in many implementations.

So, since your records aren't fixed-width, the answer is no. If they were fixed-width, you could change any record without changing the length of the line, making it more possible, but fixed-width records are a difficult thing to handle in shell!
Last edited by Corona688; 12-11-2012 at 12:09 PM..
 

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LEARN ABOUT DEBIAN

tcfmgr

TCFMGR(1)							   Tokyo Cabinet							 TCFMGR(1)

NAME

       tcfmgr - the command line utility of the fixed-length database API

DESCRIPTION

       The  command `tcfmgr' is a utility for test and debugging of the fixed-length database API and its applications.  `path' specifies the path
       of a database file.  `width' specifies the width of the value of each record.  `limsiz' specifies the limit  size  of  the  database  file.
       `key' specifies the key of a record.  `value' specifies the value of a record.  `file' specifies the input file.

	      tcfmgr create path [width [limsiz]]
		     Create a database file.
	      tcfmgr inform [-nl|-nb] path
		     Print miscellaneous information to the standard output.
	      tcfmgr put [-nl|-nb] [-sx] [-dk|-dc|-dai|-dad] path key value
		     Store a record.
	      tcfmgr out [-nl|-nb] [-sx] path key
		     Remove a record.
	      tcfmgr get [-nl|-nb] [-sx] [-px] [-pz] path key
		     Print the value of a record.
	      tcfmgr list [-nl|-nb] [-m num] [-pv] [-px] [-rb lkey ukey] [-ri str] path
		     Print keys of all records, separated by line feeds.
	      tcfmgr optimize [-nl|-nb] path [width [limsiz]]
		     Optimize a database file.
	      tcfmgr importtsv [-nl|-nb] [-sc] path [file]
		     Store records of TSV in each line of a file.
	      tcfmgr version
		     Print the version information of Tokyo Cabinet.

       Options feature the following.

	      -nl : enable the option `FDBNOLCK'.
	      -nb : enable the option `FDBLCKNB'.
	      -sx : the input data is evaluated as a hexadecimal data string.
	      -dk : use the function `tcfdbputkeep' instead of `tcfdbput'.
	      -dc : use the function `tcfdbputcat' instead of `tcfdbput'.
	      -dai : use the function `tcfdbaddint' instead of `tcfdbput'.
	      -dad : use the function `tcfdbadddouble' instead of `tcfdbput'.
	      -px : the output data is converted into a hexadecimal data string.
	      -pz : do not append line feed at the end of the output.
	      -m num : specify the maximum number of the output.
	      -pv : print values of records also.
	      -rb lkey ukey : specify the range of keys.
	      -ri str : specify the interval notation of keys.
	      -sc : normalize keys as lower cases.

       This command returns 0 on success, another on failure.

SEE ALSO

       tcftest(1), tcfmttest(1), tcfdb(3), tokyocabinet(3)

Man Page							    2011-02-12								 TCFMGR(1)
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