`--args FILENAME`: Read the file `FILENAME` and replace these two
arguments with its content. Each line of the file is assumed to be an
argument unless it starts with '-' and contains a space, in which case
it is assumed to be another flag and is treated as such. `--args
FILENAME` may be used in conjunction with any other flags.

`--case-sensitive BOOL`: Override the `case-sensitive` setting, which
can override the native preferences of the platform for case sensitive
file names: insensitive on Windows, sensitive on Unix. There are
probably odd interactions possible if you mix case sensitive and case
insensitive file systems on any single platform. This option or the
global setting should be used to force the case sensitivity to the
most sensible condition. 

`--chdir DIRECTORY`: 



`--comfmtflags NUMBER`:


`--errorlog ERRLOG`:

`--help`: If `--help` is found anywhere on the command line, translate

`FOSSIL_HOME`, `LOCALAPPDATA` (Windows), `APPDATA` (Windows),
`HOMEDRIVE` and `HOMEPATH` (Windows, used together), and `HOME` is
used as the location of the `~/.fossil` file. 

`EDITOR`: Name the editor to use for check-in and stash comments.
Overridden by the local or global `editor` setting or the `VISUAL`
environment variable.

`FOSSIL_FORCE_TICKET_MODERATION`: If set, *ALL* changes for tickets
will be required to go through moderation (even those performed by the
local interactive user via the command line).  This can be useful for
local (or remote) testing of the moderation subsystem and its impact
on the contents and status of tickets.

`FOSSIL_FORCE_WIKI_MODERATION`: If set, *ALL* changes for wiki pages
will be required to go through moderation (even those performed by the
local interactive user via the command line).  This can be useful for
local (or remote) testing of the moderation subsystem and its impact
on the contents and status of wiki pages.


`FOSSIL_HOME`: Location of the `~/.fossil` file. The first environment
variable found in the environment from the list `FOSSIL_HOME`,
`LOCALAPPDATA` (Windows), `APPDATA` (Windows), `HOMEDRIVE` and
`HOMEPATH` (Windows, used together), and `HOME` is used as the
location of the `~/.fossil` file. 

`FOSSIL_USER`: Name of the default user account if the local or global
`default-user` setting is not present. The first environment variable
found in the environment from the list `FOSSIL_USER`, `USERNAME`
(Windows), `USER`, and `LOGNAME` is the user name. If none of those
are set, then the default user name is "root".

`FOSSIL_TCL_PATH`: When Tcl stubs support is configured, point to a
specific folder containing the version of Tcl to load at run time.


`FOSSIL_VFS`: Name a VFS to load into SQLite. 

`GATEWAY_INTERFACE`: If present and the `--nocgi` option is not, assume
fossil is invoked from a web server as a CGI command, and act
accordingly.

`HOME`: Location of the `~/.fossil` file. The first environment
variable found in the environment from the list `FOSSIL_HOME`,
`LOCALAPPDATA` (Windows), `APPDATA` (Windows), `HOMEDRIVE` and
`HOMEPATH` (Windows, used together), and `HOME` is used as the
location of the `~/.fossil` file. 

`HOMEDRIVE`, `HOMEPATH`: (Windows) Location of the `~/.fossil` file.
The first environment variable found in the environment from the list
`FOSSIL_HOME`, `LOCALAPPDATA` (Windows), `APPDATA` (Windows),
`HOMEDRIVE` and `HOMEPATH` (Windows, used together), and `HOME` is
used as the location of the `~/.fossil` file. 

`HTTP_HOST`: If defined, included in error log messages.

`http_proxy`: If the global or local settings `proxy` is not set, this
is used as the default value for the `proxy` setting.


`HTTP_USER_AGENT`: If defined, included in error log messages.


`LOCALAPPDATA`: (Windows) Location of the `~/.fossil` file. The first
environment variable found in the environment from the list
`FOSSIL_HOME`, `LOCALAPPDATA` (Windows), `APPDATA` (Windows),

`REQUEST_METHOD`: If defined, included in error log messages.

`REQUEST_URI`: If defined, included in error log messages.

`SCRIPT_NAME`: If defined, included in error log messages.

`SSH_CONNECTION`: Informs CGI processing if the remote client is SSH.

`SQLITE_FORCE_PROXY_LOCKING`: From `sqlite3.c`, 1 means force always
use proxy, 0 means never use proxy, and undefined means use proxy for
non-local files only.

`SQLITE_TMPDIR`: Names the temporary file location to SQLite. 


`SYSTEMROOT`: (Windows) Used to locate `notepad.exe` as a
fall back comment editor.

`TEMP`: On Windows, the location of temporary files. The first
environment variable found in the environment that names an existing
directory from the list `TMP`, `TEMP`, `USERPROFILE`, the Windows

`TH1_DELETE_INTERP`: Set this variable to ask fossil to explicitly
delete the TH1 interpreter, if it is loaded, then check that it
released all of its allocated memory, when exiting fossil. This is not
strictly necessary, but makes debugging memory leaks easier. See
[main.c near line 386](/artifact/e75796be5338a81c?ln=386,391) for the
code.

`TH1_ENABLE_DOCS`: Override the local or global setting `tcl-docs`
to enable TH1 documents in fossil.

`TH1_ENABLE_HOOKS`: Override the local or global setting `tcl-hooks`
to enable TH1 hooks in fossil.

`TH1_ENABLE_TCL`: Override the local or global setting `tcl` to enable
TCL in fossil.

`TMP`: On Windows, the location of temporary files. The first
environment variable found in the environment that names an existing
directory from the list `TMP`, `TEMP`, `USERPROFILE`, the Windows
directory (usually `C:\WINDOWS`), `TEMP`, `TMP`, and the current
directory (aka `.`) is the temporary folder. 

`TMPDIR`: Names the temporary file location to SQLite.


`USER`: Name of the default user account if the local or global
`default-user` setting is not present. The first environment variable
found in the environment from the list `FOSSIL_USER`, `USERNAME`
(Windows), `USER`, and `LOGNAME` is the user name. If none of those
are set, then the default user name is "root".

On Unix-like platforms, if no editor is named, then a message is
displayed on stdout, and stdin is read until a single line containing
only a dot is seen.


### Default Username



When creating a new repository, fossil wants to guess a sensible user
name to make the default user granted the "s" permission.

Fossil will use the setting `default-user` if set. Normally, a local
setting would override a global setting, but when creating a new
repository it is more than a little unlikely that there is an open
checkout to provide the local setting. 

**TODO:** Any interaction caused by nesting repositories is not
documented, but should be. Similarly for simply having the current
directory inside a checkout regardless of whether the created repo
will be nested.

If `default-user` is not set, then the first found environment
variable from the list `FOSSIL_USER`, `USERNAME` (Windows), `USER`,
and `LOGNAME` is the user name. If none of those are set, then the
default user name is "root".


**TODO** Compare `db_create_default_users()` in `db.c` to
`user_select()` in `user.c` which checks in a different order...

Figure out what user is at the controls.

   1.  Use the --user and -U command-line options.

   2.  If the local database is open, check in VVAR.   ???

   3.  Check the default user in the repository (setting
   `default-user`)

   4.  Try the `FOSSIL_USER` environment variable.

   5.  Try the `USER` environment variable.

   6.  Try the `LOGNAME` environment variable.

   7.  Try the `USERNAME` environment variable.

   8.  Check if the user can be extracted from the remote URL, if
   there is a remote URL.




### Error logging

If logging errors to a file, fossil will include the values of the
following environment variables in the error log entry if they are
defined: `HTTP_HOST`, `HTTP_USER_AGENT`, `PATH_INFO`, `QUERY_STRING`,
`REMOTE_ADDR`, `REQUEST_METHOD`, `REQUEST_URI`, and `SCRIPT_NAME`. 


### Home Directory

Fossil keeps some information interesting to each user in the user's
home directory. This includes the global settings and the list of
repositories and checkouts used by `fossil all`.

The user's home directory is specified by the first environment
variable found in the environment from the list `FOSSIL_HOME`,
`LOCALAPPDATA` (Windows), `APPDATA` (Windows), `HOMEDRIVE` and
`HOMEPATH` (Windows, used together), and `HOME`. 

SQLite has its own notion of the user's home directory, which is only
exposed if the interactive SQL shell is run with the "fossil
sqlite3" command. Being a separate library, SQLite uses many of the
same variables to find the home directory, but uses them in a
different order, and does not use the `FOSSIL_HOME` variable at all.



### SQLite VFS to use

See [the SQLite documentation](http://www.sqlite.org/vfs.html) for an
explanation of what a VFS actually is and what it does.

If the default VFS underneath SQLite is not suitable, an alternative

Fossil places some temporary files in the current directory, notably
supporting files related to merge conflicts are placed in the same
folder as the merge result.

Other temporary files need a home. On Unix-like systems, the first
folder from the hard coded list `/var/tmp`, `/usr/tmp`, `/tmp`,
`/temp`, and `.` that is found to exist in the file system is used by
fossil. The SQLite library has its own code for finding a safe place for
temporary files. It checks the environment variables `SQLITE_TMPDIR`
and `TMPDIR` ahead of the hard coded list `/var/tmp`, `/usr/tmp`,
`/tmp`, and `.` for the first directory that exists.

On Windows, fossil calls [`GetTempPath`][gtp], and also queries the
environment variables `TEMP`, and `TMP`. If none of those three places
exist, then it uses `.`. Notice that `GetTempPath` itself used `TMP`,
`TEMP`, `USERPROFILE`, and the Windows folder (named in the variable
`SystemRoot`). Since the Windows folder always exists, but in modern
versions of Windows is generally *not* writable by the logged in user,
not having `TEMP`, `TMP`, or `USERPROFILE` set is almost guaranteed to
cause trouble.

[gtp]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa364992%28v=vs.85%29.aspx 



That said, it is not unusual for utilities on all platforms to assume
that `TEMP` or `TMP` point somewhere safe for temporary files.

If the identified temporary folder is not writable, then weird things
will happen on all platforms.