Linux shell script set -eux All In One
Linux shell script set -eux All In One
#!/usr/bin/env bash
# 设置 shell 选项的命令， exit, undefined, excute ❓退出，未定义，执行
set -eux
# 设置 env
# lang
# https://wttr.in/:translation
LANGUAGE="zh-CN"
CITY=Shanghai
# CITY=Moscow
UNIT=m
# UNIT=u
# m === °C (default)
# u === °F
# temperature
UA="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4343.0 Safari/537.36"
ChatGPT (GPT 3.5 free version)
prompt: 请扮演一个 Linux 系统专家来回答以下问题
Linux shell 脚本中 set -eux 是什么，有什么用处?
在Linux shell脚本中，set -eux 是一条常见的命令，用于设置脚本的执行行为。让我为您解释一下各个部分的含义和用途：
-
set：这是用于设置 shell 选项的命令。 -
-e：这是set命令的一个选项，它表示"Exitimmediately if a command exits with a non-zero status"，即如果任何命令的退出状态码（返回值）不为0，脚本将立即退出。这对于确保脚本在出现错误时立即停止执行非常有用，以防止错误的状态继续传播。 -
-u：这是set命令的另一个选项，它表示"Treatunsetvariables as an error when substituting"，即如果尝试使用未定义的变量，脚本将产生错误并退出。这有助于捕获脚本中可能导致问题的变量未正确设置的情况。 -
-x：这也是set命令的选项，它表示"Print each command beforeexecutingit"，即在执行每个命令之前，将该命令打印到标准错误输出。这对于调试脚本非常有用，因为它可以帮助您查看脚本的执行流程和变量的值。
综合起来，set -eux 是一种常用的shell脚本设置，它有助于使脚本更加健壮和易于调试。它可以帮助您在脚本执行期间捕获错误，并在脚本中使用未定义的变量时产生错误，同时还提供了执行跟踪，以便更好地理解脚本的执行流程。
https://chat.openai.com/c/d3e9ae9e-8eb7-4b00-8d6d-a16b79435a81
man set
The set command is a shell builtin command that is used to set and unset a value of the local variables in shell.
set 命令是 shell 内置命令，用于设置和取消设置 shell 中局部变量的值。
$ set [--abBCefhHkmnpPtuvx] [-o option] [arg …]
-e
Exit immediately if a pipeline (which may consist of a single simple command), a list, or a compound command (see SHELL GRAMMAR above), exits with 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 following the if or elif reserved words, 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 value 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 above), 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 functionsets -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.
-u
Treat unset variables and parameters other than the special parameters "@" and "*" as an error when performing parameter expansion.
If expansion is attempted on an unset variable or parameter, the shell prints an error message, and, if not interactive, exits with a non-zero status.
-x
After expanding each simple command, for command, case command, select command, or arithmetic for command, display the expanded value of PS4, followed by the command and its expanded arguments or associated word list.
-eExit immediately if a pipeline (which may consist of a single simple command), a list, or a compound command (see SHELL GRAMMAR above), exits with 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 following the if or elif reserved words, 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 value 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 above), 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 functionsets -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.
-uTreat unset variables and parameters other than the special parameters "@" and "*" as an error when performing parameter expansion.
If expansion is attempted on an unset variable or parameter, the shell prints an error message, and, if not interactive, exits with a non-zero status.
-xAfter expanding each simple command, for command, case command, select command, or arithmetic for command, display the expanded value of PS4, followed by the command and its expanded arguments or associated word list.
# ...
set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]
set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]
Without options, the name and value of each shell variable are displayed in a
format that can be reused as input for setting or resetting the currently-set
variables. Read-only variables cannot be reset. In posix mode, only shell
variables are listed. The output is sorted according to the current locale. When
options are specified, they set or unset shell attributes. Any arguments remaining
after option processing are treated as values for the positional parameters and are
assigned, in order, to $1, $2, ... $n. Options, if specified, have the following
meanings:
-a Each variable or function that is created or modified is given the export
attribute and marked for export to the environment of subsequent commands.
-b Report the status of terminated background jobs immediately, rather than
before the next primary prompt. This is effective only when job control is
enabled.
-e Exit immediately if a pipeline (which may consist of a single simple
command), a list, or a compound command (see SHELL GRAMMAR above), exits
with 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 following the if or elif reserved words, 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 value 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
above), 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.
-f Disable pathname expansion.
-h Remember the location of commands as they are looked up for execution.
This is enabled by default.
-k All arguments in the form of assignment statements are placed in the
environment for a command, not just those that precede the command name.
-m Monitor mode. Job control is enabled. This option is on by default for
interactive shells on systems that support it (see JOB CONTROL above). All
processes run in a separate process group. When a background job
completes, the shell prints a line containing its exit status.
-n Read commands but do not execute them. This may be used to check a shell
script for syntax errors. This is ignored by interactive shells.
-o option-name
The option-name can be one of the following:
allexport
Same as -a.
braceexpand
Same as -B.
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 the --noediting option. This also affects the editing
interface used for read -e.
errexit Same as -e.
errtrace
Same as -E.
functrace
Same as -T.
hashall Same as -h.
histexpand
Same as -H.
history Enable command history, as described above under HISTORY. This
option is on by default in interactive shells.
ignoreeof
The effect is as if the shell command ``IGNOREEOF=10'' had been
executed (see Shell Variables above).
keyword Same as -k.
monitor Same as -m.
noclobber
Same as -C.
noexec Same as -n.
noglob Same as -f.
nolog Currently ignored.
notify Same as -b.
nounset Same as -u.
onecmd Same as -t.
physical
Same as -P.
pipefail
If set, the return value of a pipeline is the value of the last
(rightmost) command to exit with a non-zero status, or zero if all
commands in the pipeline exit successfully. This option is
disabled by default.
posix Change the behavior of bash where the default operation differs
from the POSIX standard to match the standard (posix mode). See
SEE ALSO below for a reference to a document that details how posix
mode affects bash,s behavior.
privileged
Same as -p.
verbose Same as -v.
vi Use a vi-style command line editing interface. This also affects
the editing interface used for read -e.
xtrace Same as -x.
If -o is supplied with no option-name, the values of the current options
are printed. If +o is supplied with no option-name, a series of set
commands to recreate the current option settings is displayed on the
standard output.
-p Turn on privileged mode. In this mode, the $ENV and $BASH_ENV files are
not processed, shell functions are not inherited from the environment, and
the SHELLOPTS, BASHOPTS, CDPATH, and GLOBIGNORE variables, if they appear
in the environment, are ignored. If the shell is started with the
effective user (group) id not equal to the real user (group) id, and the -p
option is not supplied, these actions are taken and the effective user id
is set to the real user id. If the -p option is supplied at startup, the
effective user id is not reset. Turning this option off causes the
effective user and group ids to be set to the real user and group ids.
-t Exit after reading and executing one command.
-u Treat unset variables and parameters other than the special parameters "@"
and "*" as an error when performing parameter expansion. If expansion is
attempted on an unset variable or parameter, the shell prints an error
message, and, if not interactive, exits with a non-zero status.
-v Print shell input lines as they are read.
-x After expanding each simple command, for command, case command, select
command, or arithmetic for command, display the expanded value of PS4,
followed by the command and its expanded arguments or associated word list.
-B The shell performs brace expansion (see Brace Expansion above). This is on
by default.
-C If set, bash does not overwrite an existing file with the >, >&, and <>
redirection operators. This may be overridden when creating output files
by using the redirection operator >| instead of >.
-E If set, any trap on ERR is inherited by shell functions, command
substitutions, and commands executed in a subshell environment. The ERR
trap is normally not inherited in such cases.
-H Enable ! style history substitution. This option is on by default when
the shell is interactive.
-P If set, the shell does not resolve symbolic links when executing commands
such as cd that change the current working directory. It uses the physical
directory structure instead. By default, bash follows the logical chain of
directories when performing commands which change the current directory.
-T If set, any traps on DEBUG and RETURN are inherited by shell functions,
command substitutions, and commands executed in a subshell environment.
The DEBUG and RETURN traps are normally not inherited in such cases.
-- If no arguments follow this option, then the positional parameters are
unset. Otherwise, the positional parameters are set to the args, even if
some of them begin with a -.
- Signal the end of options, cause all remaining args to be assigned to the
positional parameters. The -x and -v options are turned off. If there are
no args, the positional parameters remain unchanged.
The options are off by default unless otherwise noted. Using + rather than -
causes these options to be turned off. The options can also be specified as
arguments to an invocation of the shell. The current set of options may be found
in $-. The return status is always true unless an invalid option is encountered.
# ...
https://manpages.ubuntu.com/manpages/jammy/en/man1/bash.1.html#shell builtin commands
https://manpages.ubuntu.com/manpages/jammy/en/man1/bash.1.html
# 查看
$ set
# 使用 pipe 直接把输出复制到系统剪切板 🚀
$ set | pbcopy
# 查看
$ set
# 使用 pipe 直接把输出复制到系统剪切板 🚀
$ set | pbcopy
'!'=0
'#'=0
'$'=76309
'*'=( )
0=-zsh
'?'=0
@=( )
ARGC=0
BG
CDPATH=''
COLUMNS=95
CPUTYPE=x86_64
EGID=20
EUID=501
FG
FIGNORE=''
FPATH=/Users/xgqfrms-mm/.oh-my-zsh/plugins/git:/Users/xgqfrms-mm/.oh-my-zsh/functions:/Users/xgqfrms-mm/.oh-my-zsh/completions:/usr/local/share/zsh/site-functions:/usr/share/zsh/site-functions:/usr/share/zsh/5.9/functions
FUNCNEST=700
FX
GID=20
HISTCHARS='!^#'
HISTCMD=6620
HISTFILE=/Users/xgqfrms-mm/.zsh_history
HISTSIZE=50000
HOME=/Users/xgqfrms-mm
HOST=xgqfrms-mm.local
IFS=$' \t\n\C-@'
KEYBOARD_HACK=''
KEYTIMEOUT=40
LC_CTYPE=UTF-8
LESS=-R
LINENO=14
LINES=68
LISTMAX=100
LOGNAME=xgqfrms-mm
MACHTYPE=x86_64
MAILCHECK=60
MAILPATH=''
MANPATH=''
MATCH=m
MBEGIN=1
MEND=1
MODULE_PATH=/usr/lib/zsh/5.9
NULLCMD=cat
NVM_BIN=/Users/xgqfrms-mm/.nvm/versions/node/v18.12.0/bin
# 省略 ...
demos
(🐞 反爬虫测试！打击盗版⚠️）如果你看到这个信息, 说明这是一篇剽窃的文章，请访问 https://www.cnblogs.com/xgqfrms/ 查看原创文章！
#!/usr/bin/env bash vs #!/usr/bin/bash vs #!/bin/bash
https://www.cnblogs.com/xgqfrms/p/17369184.html
set & unset
set [ {+|-}options | {+|-}o [ option_name ] ] ... [ {+|-}A [ name ] ]
[ arg ... ]
Set the options for the shell and/or set the positional
parameters, or declare and set an array. If the -s option is
given, it causes the specified arguments to be sorted before
assigning them to the positional parameters (or to the array
name if -A is used). With +s sort arguments in descending
order. For the meaning of the other flags, see zshoptions(1).
Flags may be specified by name using the -o option. If no option
name is supplied with -o, the current option states are printed:
see the description of setopt below for more information on the
format. With +o they are printed in a form that can be used as
input to the shell.
If the -A flag is specified, name is set to an array containing
the given args; if no name is specified, all arrays are printed
together with their values.
If +A is used and name is an array, the given arguments will
replace the initial elements of that array; if no name is
specified, all arrays are printed without their values.
The behaviour of arguments after -A name or +A name depends on
whether the option KSH_ARRAYS is set. If it is not set, all
arguments following name are treated as values for the array,
regardless of their form. If the option is set, normal option
processing continues at that point; only regular arguments are
treated as values for the array. This means that
set -A array -x -- foo
sets array to `-x -- foo' if KSH_ARRAYS is not set, but sets the
array to foo and turns on the option `-x' if it is set.
If the -A flag is not present, but there are arguments beyond
the options, the positional parameters are set. If the option
list (if any) is terminated by `--', and there are no further
arguments, the positional parameters will be unset.
If no arguments and no `--' are given, then the names and values
of all parameters are printed on the standard output. If the
only argument is `+', the names of all parameters are printed.
For historical reasons, `set -' is treated as `set +xv' and `set
- args' as `set +xv -- args' when in any other emulation mode
than zsh's native mode.
$ man zshbuiltins
# $ man zshbuiltins | grep set
# Unknown locale, assuming C
$ locale
LANG=""
LC_COLLATE="C"
LC_CTYPE="UTF-8"
LC_MESSAGES="C"
LC_MONETARY="C"
LC_NUMERIC="C"
LC_TIME="C"
LC_ALL=
# fix
$ export LANG="en_US.UTF-8"
$ locale
LANG="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_CTYPE="UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_ALL=
https://pubs.opengroup.org/onlinepubs/007904875/utilities/set.html
unset [ -fmv ] name ...
Each named parameter is unset. Local parameters remain local
even if unset; they appear unset within scope, but the previous
value will still reappear when the scope ends.
Individual elements of associative array parameters may be unset
by using subscript syntax on name, which should be quoted (or
the entire command prefixed with noglob) to protect the
subscript from filename generation.
If the -m flag is specified the arguments are taken as patterns
(should be quoted) and all parameters with matching names are
unset. Note that this cannot be used when unsetting associative
array elements, as the subscript will be treated as part of the
pattern.
The -v flag specifies that name refers to parameters. This is
the default behaviour.
unset -f is equivalent to unfunction.
https://pubs.opengroup.org/onlinepubs/007904875/utilities/unset.html
refs
https://www.baeldung.com/linux/set-command
https://askubuntu.com/questions/1455037/what-does-set-eu-do-in-a-bash-script
https://stackoverflow.com/questions/19622198/what-does-set-e-mean-in-a-bash-script
https://unix.stackexchange.com/questions/544993/what-does-set-u-do-in-bash-script
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