`-a``allexport` Automatically mark new and altered variables to be exported to subsequent environments.
`-b``notify` Don\'t wait for the next prompt to print when showing the reports for a terminated background job (only with job control)
`-e``errexit` When set, the shell exits when a simple command in a command list exits non-zero (`FALSE`). This is not done in situations, where the exit code is already checked (`if`, `while`, `until`, `||`, `&&`)
`-h``hashall` Remembers the location of commands when they\'re called (hashing). Enabled by default.
`-k``keyword` Allows to place environment-assignments everywhere in the commandline, not only infront of the called command.
`-m``monitor`**Monitor mode**. With job control, a short descriptive line is printed when a backgroud job ends. Default is \"on\" for interactive shells (with job control).
`-n``noexec` Read and parse but **do not execute commands** - useful for checking scripts for syntax errors. Ignored by interactive shells.
`-o` Set/unset attributes with long option names, e.g. `set -o noglob`. The long option names are in the second column of this table. If no option name is given, all options are printed with their current status.
`-p``privileged` Turn on privileged mode.
`-t``onecmd` Exit after reading and executing **one** command.
`-u``nounset` Treat unset variables as an error when performing parameter expansion. Non-interactive shells exit on this error.
`-v``verbose` Print shell input lines as they are read - useful for debugging.
`-x``xtrace` Print commands just before execution - with all expansions and substitutions done, and words marked - useful for debugging.
`-B``braceexpand` The shell performs [brace expansion](../../syntax/expansion/brace.md) This is on by default.
`-C` \<BOOKMARK:tag_noclobber\>`noclobber` Don\'t overwrite files on redirection operations. You can override that by specifying the `>|` redirection operator when needed. See [redirection](../../syntax/redirection.md)
`-E``errtrace``ERR`-traps are inherited by by shell functions, command substitutions, and commands executed in a subshell environment.
`-H``histexpand` Enable `!`-style history expansion. Defaults to `on` for interactive shells.
`-P``physical` Don\'t follow symlinks when changing directories - use the physical filesystem structure.
`-T``functrace``DEBUG`- and `RETURN`-traps are inherited by subsequent environments, like `-E` for `ERR` trap.
`-` \"End of options\" - all following arguments are assigned to the positional parameters, even when they begin with a dash. `-x` and `-v` options are turned off. Positional parameters are unchanged (unlike using `--`!) when no further arguments are given.
`--` If no arguments follow, the positional parameters are unset. With arguments, the positional parameters are set, even if the strings begin with a `-` (dash) like an option.
Long options usable with `-o` without a short equivalent
`emacs` Use an emacs-style command line editing interface. This is enabled by default when the shell is interactive, unless the shell is started with `--noediting` option.
`history` If set, command historization is done (enabled by default on interactive shells)
`pipefail` If set, the exit code from a pipeline is different from the normal (\"last command in pipeline\") behaviour: `TRUE` when no command failed, `FALSE` when something failed (code of the rightmost command that failed)
`posix` When set, Bash runs in POSIX mode.
`vi` Enables a `vi`-style command line editing interface.
## Examples
Tag a part of a shell script to output debugging information (`-x`):
``` bash
#!/bin/bash
...
set -x # on
...
set +x # off
...
```
## Portability considerations
`set` and its basic behaviour and options are specified by POSIX(r).
However, options that influence Bash-specific things are not portable,
