texinode(Invocation)(Files)(Introduction)(Top)
chapter(Invocation)
cindex(invocation)
sect(Invocation Options)
cindex(flags, shell)
cindex(shell flags)
The following flags are interpreted by the shell when invoked to determine
where the shell will read commands from:

startitem()
item(tt(-c))(
Take the first argument as a command to execute, rather than reading commands
from a script or standard input.  If any further arguments are given, the
first one is assigned to tt($0), rather than being used as a positional
parameter.
)
item(tt(-i))(
Force shell to be interactive.
)
item(tt(-s))(
Force shell to read commands from the standard input.
If the tt(-s) flag is not present and an argument is given,
the first argument is taken to be the pathname of a script to
execute.
)
enditem()

After the first one or two arguments have been appropriated as described above,
the remaining arguments are assigned to the positional parameters.

For further options, which are common to invocation and the tt(set)
builtin, see
ifzman(zmanref(zshoptions))\
ifnzman(noderef(Options))\
.

Options may be specified by name using the tt(-o) option.  tt(-o) acts like
a single-letter option, but takes a following string as the option name.
For example,

example(zsh -x -o shwordsplit scr)

runs the script tt(scr), setting the tt(XTRACE) option by the corresponding
letter `tt(-x)' and the tt(SH_WORD_SPLIT) option by name.
Options may be turned em(off) by name by using tt(PLUS()o) instead of tt(-o).
tt(-o) can be stacked up with preceding single-letter options, so for example
`tt(-xo shwordsplit)' or `tt(-xoshwordsplit)' is equivalent to
`tt(-x -o shwordsplit)'.

Options may also be specified by name in GNU long option style,
`tt(--)var(option-name)'.  When this is done, `tt(-)' characters in the
option name are permitted: they are translated into `tt(_)', and thus ignored.
So, for example, `tt(zsh --sh-word-split)' invokes zsh with the
tt(SH_WORD_SPLIT) option turned on.  Like other option syntaxes, options can
be turned off by replacing the initial `tt(-)' with a `tt(PLUS())'; thus
`tt(+-sh-word-split)' is equivalent to `tt(--no-sh-word-split)'.
Unlike other option syntaxes, GNU-style long options cannot be stacked with
any other options, so for example `tt(-x-shwordsplit)' is an error,
rather than being treated like `tt(-x --shwordsplit)'.

The special GNU-style option `tt(--version)' is handled; it sends to standard
output the shell's version information, then exits successfully.
`tt(--help)' is also handled; it sends to standard output a list of options
that can be used when invoking the shell, then exits successfully.

Option processing may be finished, allowing following arguments that start with
`tt(-)' or `tt(PLUS())' to be treated as normal arguments, in two ways.
Firstly, a lone `tt(-)' (or `tt(PLUS())') as an argument by itself ends option
processing.  Secondly, a special option `tt(--)' (or `tt(PLUS()-)'), which may
be specified on its own (which is the standard POSIX usage) or may be stacked
with preceding options (so `tt(-x-)' is equivalent to `tt(-x --)').  Options
are not permitted to be stacked after `tt(--)' (so `tt(-x-f)' is an error),
but note the GNU-style option form discussed above, where `tt(--shwordsplit)'
is permitted and does not end option processing.

Except when the bf(sh)/bf(ksh) emulation single-letter options are in effect,
the option `tt(-b)' (or `tt(PLUS()b)') ends option processing.
`tt(-b)' is like `tt(--)', except that further single-letter options can be
stacked after the `tt(-b)' and will take effect as normal.

startmenu()
menu(Compatibility)
menu(Restricted Shell)
endmenu()

includefile(Zsh/compat.yo)
includefile(Zsh/restricted.yo)
