The set builtin command¶
FIXME
incomplete text, examples, maybe extended description
Synopsis¶
set [--abefhkmnptuvxBCHP] <-o OPTIONNAME> [-][--] <POSPARAMS>
Description¶
set
is primarily made to
- set the positional parameters (see handling positional parameters) to
<POSPARAMS>
- set shell attributes with short options (see below)
- set shell attributes with long option names (see below)
Without any options, set
displays all shell- and environment-variables (only is POSIX-mode) in a re-usable format NAME=VALUE
.
Attributes¶
All attributes below can be switched on using -X
and switched off using +X
. This is done because of the historical meaning of the -
to set flags (true for most commands on UNIX®).
Flag | Optionname | Description |
---|---|---|
-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 , || , && ) |
-f | noglob | Disable pathname expansion (globbing) |
-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 This is on by default. |
-C | noclobber | Don't overwrite files on redirection operations. You can override that by specifying the >| redirection operator when needed. See redirection |
-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) | |
ignoreeof | The effect is as if the shell command IGNOREEOF=10 had been executed. See shell variables. | |
nolog | (currently ignored) | |
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
):
Portability considerations¶
set
and its basic behaviour and options are specified by POSIX®. However, options that influence Bash-specific things are not portable, naturally.
See also¶
- Internal: The shopt builtin command