General options:

-h, --help

Gives general summary about the command line options.

--long-help, --help-long

Gives a detailed list of command line options.

--wiki-help, --help-wiki, --mediawiki-help, --help-mediawiki

Gives a detailed list of command line options in Mediawiki format.

--version, --version-short, --short-version

Gives some version information about the program.

-i, --input <image file>

Name of the input FITS image file.

-o, --output <image file>

Name of the output FITS image file (can be the same as the input image file).

Read keyword values:

-g, --get, --read <keyword>,...

List of keywords to get from FITS header.

-F, --format <format>

Format of the output, space separated list of the arguments "filename", "keyword", "value", "comment" or "list", in the desired order. The "list" here is a list of tab-separated values of matched keywords.

-x, --extension <extension>

Read keyword values from the given extension.

Note that shell wildcard character patterns can be used in the keyword specifications.

Altering FITS headers:

-s, --set, --update <keyword>=<value>[/<comment>],...

List of keywords with their new values (and optional comments) to be altered.

-a, --append <keyword>=<value>[/<comment>],...

List of keywords with their new values (and optional comments) to be appended to the existing list of keywords.

-d, --delete <keyword>,...

List of keywords to be removed from the header.

--force-alter-reserved-keywords

Enable to alter reserved FITS keywords (use with caution).

-w, --rewrite

Re-write the input file(s) directly. Use this option exclusively from -o|--output.