.TH replacekey 1 "28 Oct 1999"
.SH NAME 
replacekey \- replace keywords in a FITS header
.SH SYNOPSIS
.B replacekey
[options] <in>
.SH DESCRIPTION
.PP
.B replacekey
is aimed at replacing keywords in a FITS file's header by
new keywords provided by the user on the command-line. 
.PP
.SH ALGORITHM
The user can provide a new_keyword, an old_keyword, a value and a comment.
.B replacekey
first searchs for old_keyword if provided. If it finds it, it replaces the
associated card by the new one (new_keyword=value/comment).
If old_keyword is either not found or not provided,
.B replacekey
searchs for new_keyword, and if it finds it, replaces the
associated card by the new one (new_keyword=value/comment).
new_keyword has to be provided.
.PP
Examples:
You want to change the value of VALUE from 32 to 16 in myfile.fits:
% replacekey -k "VALUE" -v "16" myfile.fits
.PP
If you want to replace the card with the keyword OLD by 
"NEW = 3.14 / This is a usefull key" in myfile.fits:
% replacekey -k "NEW" -v "3.14" -c "This is a usefull key" -K "OLD" myfile.fits
.PP
If your do not care about the HISTORY cards you have in the header,
and want to replace the first one by VALUE=32, you would do:
.br
% replacekey -k "VALUE" -v "32" -K "HISTORY" myfile.fits
.SH OPTIONS
.TP
.B \-k or \--key key
To provide the new keyword.
.TP
.B \-K or \--old key
To provide the old keyword.
.TP
.B \-v or \--val val
To provide the new value.
.TP
.B \-c or \--com com
To provide the new comment.
.SH SEE ALSO
.B hierarch28
to convert HIERARCH ESO keywords to regular 8-char keywords.
.SH FILES
.PP
Files shall all comply with FITS format
.SH BUGS
.PP
Modifications are so far only possible in the main header, not in the
extensions.