Difference between - and -​- in compiling options

Question

In running MiKTeX

1. What is the difference between -shell=escape and --shell-escape
2. What is the difference between -synctex=1, --synctex=1, and --synctex=-1

Answer 1

-shell=escape is invalid.

The correct syntax is the one starting with two hyphens. The versions with one hyphen (-shell-escape) often works too. But as Christian Schenk, the maintainer of MiKTeX, once wrote:

Please note that the single '-' prefixes a sequence of single-letter options (aka short options). That is, if you specify -unre, you are actually invoking these options:

--update-fndb  --print-only  --user-roots

I would recommend, tha you always specify the "long options" (prefixed by two '-'). The short options (one '-') are only for backward compatibility.

Answer 2

With regard to question no. 2: --synctex=1 creates a compressed SyncTeX file, while --synctex=-1 creates an uncompressed one. (--synctex=0 would create no SyncTeX file at all.)

Answer 3

From the command line help:

-synctex=N Generate SyncTeX data for previewers if nonzero.

-synctex and --synctex are both accepted, so all three variants enable the generation of SyncTeX data.

-shell is an unknown command-line option and produces an error.

--shell-escape seems to be silently accepted. However with MiKTeX 2.9 it is not on the list of options any more. Packages like epstopdf need to be able to “escape to a shell”. In TeX this is done via the \write18 feature. In MiKTeX it is only partially enabled by default to avoid security problems: only well known commands are allowed. You fully enable the feature by specifying --enable-write18 on the TeX command-line.