NAME

fmodcomm -- Operates upon an input FITS file by modifying the text of commentary keywords in the header of the primary array or an extension.


USAGE

        fmodcomm infile[ext#] template newtext

DESCRIPTION

This task modifies the text in any of the three commentary keywords (COMMENT, HISTORY, or <blank>) in the header of the input FITS file. A unique substring (plus its keyword type) specifies the particular line to be modified. If two or more lines are identical, then a match to the first line can be forced by setting the "firstmatch" parameter. New text provided by the user replaces the original text. If the new text is too long to fit on a single line, additional lines of the same keyword type are inserted. New text (up to 99 lines) can be read in from a file via the @filename convention.


PARAMETERS

infile [string]
The name (including extension number in square brackets or after a +) of the input FITS file which is to be modified. The user must have write privilege to this file.

template [string]
Text which is matched against all header records of the specified keyword type to identify the line to be modified.

newtext [string]
The text which is put in place of the *entire* header line matched by template and keytype. If longer than 70 characters (up to 350), extra header records of the same keyword type are inserted as necessary. If @filename is given instead, up to 99 lines of text will be read from filename and replace the template line.

(keytype="COMMENT") [string]
Specifies which of the three commentary keywords should be acted upon [COMMENT, HISTORY, or <blank>]. Only the first letter is required, case insensitive.

(firstmatch = no) [boolean]
If identical header lines exist, then action can be forced by setting this to yes; the first matching line will then be acted upon.


EXAMPLES

1. Modify the myfile.fits file which contains the following record in the primary array header to correct the date to 1995: 

        COMMENT   Data derived from AJ 109, 1697 (1994)


        ft> fmodcomm myfile.fits+0 "AJ" "Data derived from AJ 109, 1697 (1995)"

This will find a COMMENT line in the primary array header containing the substring "AJ" and replace that line with "Data derived....(1995)"

2. Modify the myfile.fits file which contains the following records in the first extension so as to sandwich additional text between them: 

        HISTORY   Input PHA spectrum file = SCRABK.PHA
        HISTORY   TASK: FEXTRACT on FILENAME: crabk.fits


        ft> fmodcomm myfile.fits+1 "PHA spec" @tmp keytype=HISTORY

where the file named tmp contains: 

        Input PHA spectrum file = SCRABK.PHA
        This is an extra line of text
        So is this one
        And finally this one

yields: 

        HISTORY   Input PHA spectrum file = SCRABK.PHA
        HISTORY   This is an extra line of text
        HISTORY   So is this one
        HISTORY   And finally this one
        HISTORY   TASK: FEXTRACT on FILENAME: crabk.fits


BUGS


SEE ALSO

fthedit. fv, the interactive FITS file editor, can also be used to modify commentary keywords.

CATEGORY

Jun95 ftools.futils