What does set -e and set -a do in bash.What are other options that i can use with set command
我想知道下面的命令在bash中做什么。
- 集合E
- 集合A
我可以在set中使用的其他选项是什么?它们是什么意思?
试运行:
1 | help set |
输出为:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | set: set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...] Set or unset values of shell options and positional parameters. Change the value of shell attributes and positional parameters, or display the names and values of shell variables. Options: -a Mark variables which are modified or created for export. -b Notify of job termination immediately. -e Exit immediately if a command exits with a non-zero status. -f Disable file name generation (globbing). -h Remember the location of commands as they are looked up. -k All assignment arguments are placed in the environment for a command, not just those that precede the command name. -m Job control is enabled. -n Read commands but do not execute them. -o option-name Set the variable corresponding to option-name: allexport same as -a braceexpand same as -B emacs use an emacs-style line editing interface errexit same as -e errtrace same as -E functrace same as -T hashall same as -h histexpand same as -H history enable command history ignoreeof the shell will not exit upon reading EOF interactive-comments allow comments to appear in interactive commands keyword same as -k monitor same as -m noclobber same as -C noexec same as -n noglob same as -f nolog currently accepted but ignored notify same as -b nounset same as -u onecmd same as -t physical same as -P pipefail the return value of a pipeline is the status of the last command to exit with a non-zero status, or zero if no command exited with a non-zero status posix change the behavior of bash where the default operation differs from the Posix standard to match the standard privileged same as -p verbose same as -v vi use a vi-style line editing interface xtrace same as -x -p Turned on whenever the real and effective user ids do not match. Disables processing of the $ENV file and importing of shell functions. Turning this option off causes the effective uid and gid to be set to the real uid and gid. -t Exit after reading and executing one command. -u Treat unset variables as an error when substituting. -v Print shell input lines as they are read. -x Print commands and their arguments as they are executed. -B the shell will perform brace expansion -C If set, disallow existing regular files to be overwritten by redirection of output. -E If set, the ERR trap is inherited by shell functions. -H Enable ! style history substitution. This flag is on by default when the shell is interactive. -P If set, do not resolve symbolic links when executing commands such as cd which change the current directory. -T If set, the DEBUG trap is inherited by shell functions. -- Assign any remaining arguments to the positional parameters. If there are no remaining arguments, the positional parameters are unset. - Assign any remaining arguments to the positional parameters. The -x and -v options are turned off. Using + rather than - causes these flags to be turned off. The flags can also be used upon invocation of the shell. The current set of flags may be found in $-. The remaining n ARGs are positional parameters and are assigned, in order, to $1, $2, .. $n. If no ARGs are given, all shell variables are printed. Exit Status: Returns success unless an invalid option is given. |
从手册页:
-a Mark variables and function which are modified or created for export to the environment of subsequent commands
-e Exit immediately if a pipeline (see Pipelines), which may consist of a single simple command (see Simple Commands), a list (see Lists),
or a compound command (see Compound Commands) returns a non-zero
status. The shell does not exit if the command that fails is part of
the command list immediately following a while or until keyword, part
of the test in an if statement, part of any command executed in a &&
or || list except the command following the final && or ||, any
command in a pipeline but the last, or if the command’s return status
is being inverted with !. If a compound command other than a subshell
returns a non-zero status because a command failed while -e was being
ignored, the shell does not exit. A trap on ERR, if set, is executed
before the shell exits.This option applies to the shell environment and each subshell
environment separately (see Command Execution Environment), and may
cause subshells to exit before executing all the commands in the
subshell.If a compound command or shell function executes in a context where -e
is being ignored, none of the commands executed within the compound
command or function body will be affected by the -e setting, even if
-e is set and a command returns a failure status. If a compound command or shell function sets -e while executing in a context where
-e is ignored, that setting will not have any effect until the compound command or the command containing the function call
completes.