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Bash中的错误处理

你最喜欢在Bash中处理错误的方法是什么?我在网上找到的处理错误的最好例子是由William Shotts,Jr在 http://www.linuxcommand.org 编写的。

他建议在Bash中使用以下函数进行错误处理:

#!/bin/bash

# A slicker error handling routine

# I put a variable in my scripts named PROGNAME which
# holds the name of the program being run.  You can get this
# value from the first item on the command line ($0).

# Reference: This was copied from <http://www.linuxcommand.org/wss0150.php>

PROGNAME=$(basename $0)

function error_exit
{

#   ----------------------------------------------------------------
#   Function for exit due to fatal program error
#       Accepts 1 argument:
#           string containing descriptive error message
#   ---------------------------------------------------------------- 

    echo "${PROGNAME}: ${1:-"Unknown Error"}" 1>&2
    exit 1
}

# Example call of the error_exit function.  Note the inclusion
# of the LINENO environment variable.  It contains the current
# line number.

echo "Example of error with line number and message"
error_exit "$LINENO: An error has occurred."

您是否有更好的错误处理例程,您在Bash脚本中使用?

210
Noob

使用陷阱!

tempfiles=( )
cleanup() {
  rm -f "${tempfiles[@]}"
}
trap cleanup 0

error() {
  local parent_lineno="$1"
  local message="$2"
  local code="${3:-1}"
  if [[ -n "$message" ]] ; then
    echo "Error on or near line ${parent_lineno}: ${message}; exiting with status ${code}"
  else
    echo "Error on or near line ${parent_lineno}; exiting with status ${code}"
  fi
  exit "${code}"
}
trap 'error ${LINENO}' ERR

...然后,每当您创建临时文件时:

temp_foo="$(mktemp -t foobar.XXXXXX)"
tempfiles+=( "$temp_foo" )

退出时将删除$temp_foo,并打印当前行号。 (set -e同样会给你退出错误行为, 虽然它带有严重的警告 并削弱了代码的可预测性和可移植性)。

您可以让陷阱为您调用error(在这种情况下,它使用默认退出代码1并且没有消息)或自己调用它并提供显式值;例如:

error ${LINENO} "the foobar failed" 2

将以状态2退出,并给出明确的消息。

143
Charles Duffy

这是一个很好的解决方案。我只是想补充一下

set -e

作为一种基本的错误机制。如果简单命令失败,它将立即停止您的脚本。我认为这应该是默认行为:因为这样的错误几乎总是表示意外的事情,所以继续执行以下命令并不是真的“理智”。

112
Bruno De Fraine

阅读本页面上的所有答案都给了我很多启发。

所以,这是我的提示:

文件内容:lib.trap.sh

lib_name='trap'
lib_version=20121026

stderr_log="/dev/shm/stderr.log"

#
# TO BE SOURCED ONLY ONCE:
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

if test "${g_libs[$lib_name]+_}"; then
    return 0
else
    if test ${#g_libs[@]} == 0; then
        declare -A g_libs
    fi
    g_libs[$lib_name]=$lib_version
fi


#
# MAIN CODE:
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
set -o nounset   ## set -u : exit the script if you try to use an uninitialised variable
set -o errexit   ## set -e : exit the script if any statement returns a non-true return value

exec 2>"$stderr_log"


###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##
#
# FUNCTION: EXIT_HANDLER
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

function exit_handler ()
{
    local error_code="$?"

    test $error_code == 0 && return;

    #
    # LOCAL VARIABLES:
    # ------------------------------------------------------------------
    #    
    local i=0
    local regex=''
    local mem=''

    local error_file=''
    local error_lineno=''
    local error_message='unknown'

    local lineno=''


    #
    # PRINT THE HEADER:
    # ------------------------------------------------------------------
    #
    # Color the output if it's an interactive terminal
    test -t 1 && tput bold; tput setf 4                                 ## red bold
    echo -e "\n(!) EXIT HANDLER:\n"


    #
    # GETTING LAST ERROR OCCURRED:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    #
    # Read last file from the error log
    # ------------------------------------------------------------------
    #
    if test -f "$stderr_log"
        then
            stderr=$( tail -n 1 "$stderr_log" )
            rm "$stderr_log"
    fi

    #
    # Managing the line to extract information:
    # ------------------------------------------------------------------
    #

    if test -n "$stderr"
        then        
            # Exploding stderr on :
            mem="$IFS"
            local shrunk_stderr=$( echo "$stderr" | sed 's/\: /\:/g' )
            IFS=':'
            local stderr_parts=( $shrunk_stderr )
            IFS="$mem"

            # Storing information on the error
            error_file="${stderr_parts[0]}"
            error_lineno="${stderr_parts[1]}"
            error_message=""

            for (( i = 3; i <= ${#stderr_parts[@]}; i++ ))
                do
                    error_message="$error_message "${stderr_parts[$i-1]}": "
            done

            # Removing last ':' (colon character)
            error_message="${error_message%:*}"

            # Trim
            error_message="$( echo "$error_message" | sed -e 's/^[ \t]*//' | sed -e 's/[ \t]*$//' )"
    fi

    #
    # GETTING BACKTRACE:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
    _backtrace=$( backtrace 2 )


    #
    # MANAGING THE OUTPUT:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    local lineno=""
    regex='^([a-z]{1,}) ([0-9]{1,})$'

    if [[ $error_lineno =~ $regex ]]

        # The error line was found on the log
        # (e.g. type 'ff' without quotes wherever)
        # --------------------------------------------------------------
        then
            local row="${BASH_REMATCH[1]}"
            lineno="${BASH_REMATCH[2]}"

            echo -e "FILE:\t\t${error_file}"
            echo -e "${row^^}:\t\t${lineno}\n"

            echo -e "ERROR CODE:\t${error_code}"             
            test -t 1 && tput setf 6                                    ## white yellow
            echo -e "ERROR MESSAGE:\n$error_message"


        else
            regex="^${error_file}\$|^${error_file}\s+|\s+${error_file}\s+|\s+${error_file}\$"
            if [[ "$_backtrace" =~ $regex ]]

                # The file was found on the log but not the error line
                # (could not reproduce this case so far)
                # ------------------------------------------------------
                then
                    echo -e "FILE:\t\t$error_file"
                    echo -e "ROW:\t\tunknown\n"

                    echo -e "ERROR CODE:\t${error_code}"
                    test -t 1 && tput setf 6                            ## white yellow
                    echo -e "ERROR MESSAGE:\n${stderr}"

                # Neither the error line nor the error file was found on the log
                # (e.g. type 'cp ffd fdf' without quotes wherever)
                # ------------------------------------------------------
                else
                    #
                    # The error file is the first on backtrace list:

                    # Exploding backtrace on newlines
                    mem=$IFS
                    IFS='
                    '
                    #
                    # Substring: I keep only the carriage return
                    # (others needed only for tabbing purpose)
                    IFS=${IFS:0:1}
                    local lines=( $_backtrace )

                    IFS=$mem

                    error_file=""

                    if test -n "${lines[1]}"
                        then
                            array=( ${lines[1]} )

                            for (( i=2; i<${#array[@]}; i++ ))
                                do
                                    error_file="$error_file ${array[$i]}"
                            done

                            # Trim
                            error_file="$( echo "$error_file" | sed -e 's/^[ \t]*//' | sed -e 's/[ \t]*$//' )"
                    fi

                    echo -e "FILE:\t\t$error_file"
                    echo -e "ROW:\t\tunknown\n"

                    echo -e "ERROR CODE:\t${error_code}"
                    test -t 1 && tput setf 6                            ## white yellow
                    if test -n "${stderr}"
                        then
                            echo -e "ERROR MESSAGE:\n${stderr}"
                        else
                            echo -e "ERROR MESSAGE:\n${error_message}"
                    fi
            fi
    fi

    #
    # PRINTING THE BACKTRACE:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    test -t 1 && tput setf 7                                            ## white bold
    echo -e "\n$_backtrace\n"

    #
    # EXITING:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    test -t 1 && tput setf 4                                            ## red bold
    echo "Exiting!"

    test -t 1 && tput sgr0 # Reset terminal

    exit "$error_code"
}
trap exit_handler EXIT                                                  # ! ! ! TRAP EXIT ! ! !
trap exit ERR                                                           # ! ! ! TRAP ERR ! ! !


###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##
#
# FUNCTION: BACKTRACE
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

function backtrace
{
    local _start_from_=0

    local params=( "[email protected]" )
    if (( "${#params[@]}" >= "1" ))
        then
            _start_from_="$1"
    fi

    local i=0
    local first=false
    while caller $i > /dev/null
    do
        if test -n "$_start_from_" && (( "$i" + 1   >= "$_start_from_" ))
            then
                if test "$first" == false
                    then
                        echo "BACKTRACE IS:"
                        first=true
                fi
                caller $i
        fi
        let "i=i+1"
    done
}

return 0



使用示例:
文件内容:trap-test.sh

#!/bin/bash

source 'lib.trap.sh'

echo "doing something wrong now .."
echo "$foo"

exit 0


运行:

bash trap-test.sh

输出:

doing something wrong now ..

(!) EXIT HANDLER:

FILE:       trap-test.sh
LINE:       6

ERROR CODE: 1
ERROR MESSAGE:
foo:   unassigned variable

BACKTRACE IS:
1 main trap-test.sh

Exiting!


正如您在下面的屏幕截图中看到的那样,输出是彩色的,错误消息以使用的语言显示。

enter image description here

71
Luca Borrione

“set -e”的等效替代方法是

set -o errexit

它使旗帜的含义比“-e”更清晰。

随机添加:暂时禁用该标志,并返回默认值(无论退出代码如何继续执行),只需使用即可

set +e
echo "commands run here returning non-zero exit codes will not cause the entire script to fail"
echo "false returns 1 as an exit code"
false
set -e

这排除了其他响应中提到的正确错误处理,但是快速有效(就像bash一样)。

22
Ben Scholbrock

受到这里提出的想法的启发,我开发了一种可读且方便的方法来处理我的bash脚本中的错误 bash样板项目

通过简单地获取库,您可以获得以下开箱即用(即,它将暂停执行任何错误,就像使用set -e一样,感谢trap上的ERR和一些bash-fu):

bash-oo-framework error handling

有一些额外的功能可以帮助处理错误,比如 try和catch ,或者 throw keyword,它允许你在一个点上中断执行以查看回溯。此外,如果终端支持它,它会吐出powerline表情符号,为输出的颜色部分着色以提高可读性,并强调在代码行的上下文中导致异常的方法。

缺点是 - 它不可移植 - 代码在bash中工作,可能只有> = 4(但我想它可以通过一些努力来移植bash 3)。

代码被分成多个文件以便更好地处理,但我受到了回溯思想的启发 Luca Borrione的上述答案

要阅读更多信息或查看源代码,请参阅GitHub:

https://github.com/niieani/bash-oo-framework#error-handling-with-exceptions-and-throw

19
niieani

我更喜欢一些很容易打电话的东西。所以我使用的东西看起来有点复杂,但很容易使用。我通常只是将下面的代码复制并粘贴到我的脚本中。代码后面有一个解释。

#This function is used to cleanly exit any script. It does this displaying a
# given error message, and exiting with an error code.
function error_exit {
    echo
    echo "[email protected]"
    exit 1
}
#Trap the killer signals so that we can exit with a good message.
trap "error_exit 'Received signal SIGHUP'" SIGHUP
trap "error_exit 'Received signal SIGINT'" SIGINT
trap "error_exit 'Received signal SIGTERM'" SIGTERM

#Alias the function so that it will print a message with the following format:
#prog-name(@line#): message
#We have to explicitly allow aliases, we do this because they make calling the
#function much easier (see example).
shopt -s expand_aliases
alias die='error_exit "Error ${0}(@`echo $(( $LINENO - 1 ))`):"'

我通常在error_exit函数的一侧调用清理函数,但这在脚本之间有所不同,所以我把它遗漏了。陷阱捕获常见的终止信号并确保一切都得到清理。别名是真正的魔力。我想检查一切是否失败。所以一般来说我用“if!”调用程序。类型声明。通过从行号中减去1,别名将告诉我故障发生的位置。打电话也很简单,而且非常白痴。下面是一个示例(只需将/ bin/false替换为您要调用的任何内容)。

#This is an example useage, it will print out
#Error prog-name (@1): Who knew false is false.
if ! /bin/false ; then
    die "Who knew false is false."
fi
11
Michael Nooner

另一个考虑因素是返回的退出代码。只是“1”是相当标准的,虽然有一些 保留退出代码,bash本身使用 ,并且同一页面认为用户定义的代码应该在64-113范围内以符合C/C++标准。

您可能还会考虑mount用于其退出代码的位向量方法:

 0  success
 1  incorrect invocation or permissions
 2  system error (out of memory, cannot fork, no more loop devices)
 4  internal mount bug or missing nfs support in mount
 8  user interrupt
16  problems writing or locking /etc/mtab
32  mount failure
64  some mount succeeded

OR将代码放在一起允许您的脚本发出多个同时发生的错误信号。

6
yukondude

我使用以下陷阱代码,它还允许 通过管道和'时间'命令来跟踪错误

#!/bin/bash
set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
function error() {
    JOB="$0"              # job name
    LASTLINE="$1"         # line of error occurrence
    LASTERR="$2"          # error code
    echo "ERROR in ${JOB} : line ${LASTLINE} with exit code ${LASTERR}"
    exit 1
}
trap 'error ${LINENO} ${?}' ERR
4
Olivier Delrieu

我用过

die() {
        echo $1
        kill $$
}

之前;我认为因为某些原因'退出'对我失败了。不过,上述默认值似乎是一个好主意。

3
pjz

这个 现在已经很好地服务了我一段时间。它以红色打印错误或警告消息,每个参数一行,并允许可选的退出代码。

# Custom errors
EX_UNKNOWN=1

warning()
{
    # Output warning messages
    # Color the output red if it's an interactive terminal
    # @param $1...: Messages

    test -t 1 && tput setf 4

    printf '%s\n' "[email protected]" >&2

    test -t 1 && tput sgr0 # Reset terminal
    true
}

error()
{
    # Output error messages with optional exit code
    # @param $1...: Messages
    # @param $N: Exit code (optional)

    messages=( "[email protected]" )

    # If the last parameter is a number, it's not part of the messages
    last_parameter="${messages[@]: -1}"
    if [[ "$last_parameter" =~ ^[0-9]*$ ]]
    then
        exit_code=$last_parameter
        unset messages[$((${#messages[@]} - 1))]
    fi

    warning "${messages[@]}"

    exit ${exit_code:-$EX_UNKNOWN}
}
3
l0b0

不确定这对你是否有帮助,但我在这里修改了一些建议的功能,以便在其中包含对错误的检查(来自先前命令的退出代码)。在每次“检查”时,我还将错误用于记录目的的“消息”作为参数传递。

#!/bin/bash

error_exit()
{
    if [ "$?" != "0" ]; then
        log.sh "$1"
        exit 1
    fi
}

现在在同一个脚本中调用它(或者如果我使用export -f error_exit则在另一个脚本中调用)我只需编写函数的名称并将消息作为参数传递,如下所示:

#!/bin/bash

cd /home/myuser/afolder
error_exit "Unable to switch to folder"

rm *
error_exit "Unable to delete all files"

使用这个我能够为一些自动化过程创建一个非常强大的bash文件,它会在出现错误时停止并通知我(log.sh会这样做)

2
Nelson Rodriguez

这个功能最近为我提供了很好的服务:

action () {
    # Test if the first parameter is non-zero
    # and return straight away if so
    if test $1 -ne 0
    then
        return $1
    fi

    # Discard the control parameter
    # and execute the rest
    shift 1
    "[email protected]"
    local status=$?

    # Test the exit status of the command run
    # and display an error message on failure
    if test ${status} -ne 0
    then
        echo Command \""[email protected]"\" failed >&2
    fi

    return ${status}
}

您可以通过将0或最后一个返回值附加到要运行的命令的名称来调用它,这样您就可以链接命令而无需检查错误值。有了这个,这句话块:

command1 param1 param2 param3...
command2 param1 param2 param3...
command3 param1 param2 param3...
command4 param1 param2 param3...
command5 param1 param2 param3...
command6 param1 param2 param3...

变成这样:

action 0 command1 param1 param2 param3...
action $? command2 param1 param2 param3...
action $? command3 param1 param2 param3...
action $? command4 param1 param2 param3...
action $? command5 param1 param2 param3...
action $? command6 param1 param2 param3...

<<<Error-handling code here>>>

如果任何命令失败,则错误代码将简单地传递到块的末尾。如果前一个命令失败,你不希望后续命令执行,但你也不希望脚本立即退出(例如,在循环内),我发现它很有用。

1
xarxziux

这个技巧对于缺少命令或功能很有用。缺少的函数(或可执行文件)的名称将在$ _中传递

function handle_error {
    status=$?
    last_call=$1

    # 127 is 'command not found'
    (( status != 127 )) && return

    echo "you tried to call $last_call"
    return
}

# Trap errors.
trap 'handle_error "$_"' ERR
0
Orwellophile

使用陷阱并不总是一种选择。例如,如果您正在编写某种需要错误处理的可重用函数,并且可以从任何脚本调用(在使用辅助函数获取文件之后),则该函数不能假设外部脚本的退出时间,这使得使用陷阱非常困难。使用陷阱的另一个缺点是可组合性差,因为您可能会覆盖可能在调用者链中早先设置的先前陷阱。

有一个小技巧可用于在没有陷阱的情况下进行正确的错误处理。正如你可能从其他答案中已经知道的那样,如果在它们之后使用set -e运算符,||在命令内部不起作用,即使你在子shell中运行它们也是如此;例如,这不起作用:

#!/bin/sh

# prints:
#
# --> outer
# --> inner
# ./so_1.sh: line 16: some_failed_command: command not found
# <-- inner
# <-- outer

set -e

outer() {
  echo '--> outer'
  (inner) || {
    exit_code=$?
    echo '--> cleanup'
    return $exit_code
  }
  echo '<-- outer'
}

inner() {
  set -e
  echo '--> inner'
  some_failed_command
  echo '<-- inner'
}

outer

但是需要||运算符来防止在清理之前从外部函数返回。诀窍是在后台运行内部命令,然后立即等待它。 wait builtin将返回内部命令的退出代码,现在你在wait之后使用||,而不是内部函数,所以set -e在后者内部正常工作:

#!/bin/sh

# prints:
#
# --> outer
# --> inner
# ./so_2.sh: line 27: some_failed_command: command not found
# --> cleanup

set -e

outer() {
  echo '--> outer'
  inner &
  wait $! || {
    exit_code=$?
    echo '--> cleanup'
    return $exit_code
  }
  echo '<-- outer'
}

inner() {
  set -e
  echo '--> inner'
  some_failed_command
  echo '<-- inner'
}

outer

这是基于这个想法的通用函数。如果删除local关键字,它应该适用于所有与POSIX兼容的shell,即仅用local x=y替换所有x=y

# [CLEANUP=cleanup_cmd] run cmd [args...]
#
# `cmd` and `args...` A command to run and its arguments.
#
# `cleanup_cmd` A command that is called after cmd has exited,
# and gets passed the same arguments as cmd. Additionally, the
# following environment variables are available to that command:
#
# - `RUN_CMD` contains the `cmd` that was passed to `run`;
# - `RUN_EXIT_CODE` contains the exit code of the command.
#
# If `cleanup_cmd` is set, `run` will return the exit code of that
# command. Otherwise, it will return the exit code of `cmd`.
#
run() {
  local cmd="$1"; shift
  local exit_code=0

  local e_was_set=1; if ! is_Shell_attribute_set e; then
    set -e
    e_was_set=0
  fi

  "$cmd" "[email protected]" &

  wait $! || {
    exit_code=$?
  }

  if [ "$e_was_set" = 0 ] && is_Shell_attribute_set e; then
    set +e
  fi

  if [ -n "$CLEANUP" ]; then
    RUN_CMD="$cmd" RUN_EXIT_CODE="$exit_code" "$CLEANUP" "[email protected]"
    return $?
  fi

  return $exit_code
}


is_Shell_attribute_set() { # attribute, like "x"
  case "$-" in
    *"$1"*) return 0 ;;
    *)    return 1 ;;
  esac
}

用法示例:

#!/bin/sh
set -e

# Source the file with the definition of `run` (previous code snippet).
# Alternatively, you may paste that code directly here and comment the next line.
. ./utils.sh


main() {
  echo "--> main: [email protected]"
  CLEANUP=cleanup run inner "[email protected]"
  echo "<-- main"
}


inner() {
  echo "--> inner: [email protected]"
  sleep 0.5; if [ "$1" = 'fail' ]; then
    oh_my_god_look_at_this
  fi
  echo "<-- inner"
}


cleanup() {
  echo "--> cleanup: [email protected]"
  echo "    RUN_CMD = '$RUN_CMD'"
  echo "    RUN_EXIT_CODE = $RUN_EXIT_CODE"
  sleep 0.3
  echo '<-- cleanup'
  return $RUN_EXIT_CODE
}

main "[email protected]"

运行示例:

$ ./so_3 fail; echo "exit code: $?"

--> main: fail
--> inner: fail
./so_3: line 15: oh_my_god_look_at_this: command not found
--> cleanup: fail
    RUN_CMD = 'inner'
    RUN_EXIT_CODE = 127
<-- cleanup
exit code: 127

$ ./so_3 pass; echo "exit code: $?"

--> main: pass
--> inner: pass
<-- inner
--> cleanup: pass
    RUN_CMD = 'inner'
    RUN_EXIT_CODE = 0
<-- cleanup
<-- main
exit code: 0

使用此方法时,您唯一需要注意的是,从传递给run的命令完成的Shell变量的所有修改都不会传播到调用函数,因为该命令在子shell中运行。

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skozin