对于多个命令，是否有类似于pipefail的东西，比如'try'语句，但在bash中。我想这样做:
echo "trying stuff"
try {
command1
command2
command3
}
在任何时候，如果任何命令失败了，就退出并回显该命令的错误。我不想做这样的事情:
command1
if [ $? -ne 0 ]; then
echo "command1 borked it"
fi
command2
if [ $? -ne 0 ]; then
echo "command2 borked it"
fi
等等……或者类似的事情:
pipefail -o
command1 "arg1" "arg2" | command2 "arg1" "arg2" | command3
因为我相信每个命令的参数(如果我错了请纠正我)会相互干扰。这两种方法对我来说似乎非常冗长和讨厌，所以我在这里呼吁一种更有效的方法。
run() {
$*
if [ $? -ne 0 ]
then
echo "$* failed with exit code $?"
return 1
else
return 0
fi
}
run command1 && run command2 && run command3
您可以编写一个函数来启动和测试该命令。假设command1和command2是已设置为命令的环境变量。
function mytest {
"$@"
local status=$?
if (( status != 0 )); then
echo "error with $1" >&2
fi
return $status
}
mytest "$command1"
mytest "$command2"
你说的“退出并回复错误”是什么意思?如果您的意思是希望脚本在任何命令失败时立即终止，那么就这样做
set -e # DON'T do this. See commentary below.
在脚本的开头(但注意下面的警告)。不要回显错误消息:让失败的命令处理它。换句话说，如果你这样做:
#!/bin/sh
set -e # Use caution. eg, don't do this
command1
command2
command3
而command2失败，同时打印一个错误消息到stderr，那么似乎您已经实现了您想要的。(除非我误解了你想要的!)
因此，您编写的任何命令都必须表现良好:它必须向stderr而不是stdout报告错误(问题中的示例代码将错误输出到stdout)，并且在失败时必须以非零状态退出。
However, I no longer consider this to be a good practice. set -e has changed its semantics with different versions of bash, and although it works fine for a simple script, there are so many edge cases that it is essentially unusable. (Consider things like: set -e; foo() { false; echo should not print; } ; foo && echo ok The semantics here are somewhat reasonable, but if you refactor code into a function that relied on the option setting to terminate early, you can easily get bitten.) IMO it is better to write:
#!/bin/sh
command1 || exit
command2 || exit
command3 || exit
or
#!/bin/sh
command1 && command2 && command3
不要创建runner函数或使用set -e，而是使用trap:
trap 'echo "error"; do_cleanup failed; exit' ERR
trap 'echo "received signal to stop"; do_cleanup interrupted; exit' SIGQUIT SIGTERM SIGINT
do_cleanup () { rm tempfile; echo "$1 $(date)" >> script_log; }
command1
command2
command3
该trap甚至可以访问触发它的命令的行号和命令行。变量为$BASH_LINENO和$BASH_COMMAND。
我有一组在Red Hat系统上广泛使用的脚本函数。它们使用/etc/init.中的系统功能d/函数输出绿色[OK]和红色[FAILED]状态指示灯。
如果您想记录哪些命令失败，您可以选择将$LOG_STEPS变量设置为日志文件名。
使用
step "Installing XFS filesystem tools:"
try rpm -i xfsprogs-*.rpm
next
step "Configuring udev:"
try cp *.rules /etc/udev/rules.d
try udevtrigger
next
step "Adding rc.postsysinit hook:"
try cp rc.postsysinit /etc/rc.d/
try ln -s rc.d/rc.postsysinit /etc/rc.postsysinit
try echo $'\nexec /etc/rc.postsysinit' >> /etc/rc.sysinit
next
输出
Installing XFS filesystem tools: [ OK ]
Configuring udev: [FAILED]
Adding rc.postsysinit hook: [ OK ]
Code
#!/bin/bash
. /etc/init.d/functions
# Use step(), try(), and next() to perform a series of commands and print
# [ OK ] or [FAILED] at the end. The step as a whole fails if any individual
# command fails.
#
# Example:
# step "Remounting / and /boot as read-write:"
# try mount -o remount,rw /
# try mount -o remount,rw /boot
# next
step() {
echo -n "$@"
STEP_OK=0
[[ -w /tmp ]] && echo $STEP_OK > /tmp/step.$$
}
try() {
# Check for `-b' argument to run command in the background.
local BG=
[[ $1 == -b ]] && { BG=1; shift; }
[[ $1 == -- ]] && { shift; }
# Run the command.
if [[ -z $BG ]]; then
"$@"
else
"$@" &
fi
# Check if command failed and update $STEP_OK if so.
local EXIT_CODE=$?
if [[ $EXIT_CODE -ne 0 ]]; then
STEP_OK=$EXIT_CODE
[[ -w /tmp ]] && echo $STEP_OK > /tmp/step.$$
if [[ -n $LOG_STEPS ]]; then
local FILE=$(readlink -m "${BASH_SOURCE[1]}")
local LINE=${BASH_LINENO[0]}
echo "$FILE: line $LINE: Command \`$*' failed with exit code $EXIT_CODE." >> "$LOG_STEPS"
fi
fi
return $EXIT_CODE
}
next() {
[[ -f /tmp/step.$$ ]] && { STEP_OK=$(< /tmp/step.$$); rm -f /tmp/step.$$; }
[[ $STEP_OK -eq 0 ]] && echo_success || echo_failure
echo
return $STEP_OK
}
不管怎样，编写代码来检查每个命令是否成功的更简单的方法是:
command1 || echo "command1 borked it"
command2 || echo "command2 borked it"
它仍然很乏味，但至少是可读的。
对不起，我不能对第一个答案发表评论 但是你应该使用新实例来执行命令:
#!/bin/bash
function check_exit {
cmd_output=$($@)
local status=$?
echo $status
if [ $status -ne 0 ]; then
echo "error with $1" >&2
fi
return $status
}
function run_command() {
exit 1
}
check_exit run_command
就我个人而言，我更喜欢使用轻量级方法，如下所示;
yell() { echo "$0: $*" >&2; }
die() { yell "$*"; exit 111; }
try() { "$@" || die "cannot $*"; }
asuser() { sudo su - "$1" -c "${*:2}"; }
使用示例:
try apt-fast upgrade -y
try asuser vagrant "echo 'uname -a' >> ~/.profile"
我已经在bash中开发了一个几乎完美无缺的try & catch实现，它允许您编写如下代码:
try
echo 'Hello'
false
echo 'This will not be displayed'
catch
echo "Error in $__EXCEPTION_SOURCE__ at line: $__EXCEPTION_LINE__!"
您甚至可以将try-catch块嵌套在它们自己内部!
try {
echo 'Hello'
try {
echo 'Nested Hello'
false
echo 'This will not execute'
} catch {
echo "Nested Caught (@ $__EXCEPTION_LINE__)"
}
false
echo 'This will not execute too'
} catch {
echo "Error in $__EXCEPTION_SOURCE__ at line: $__EXCEPTION_LINE__!"
}
代码是bash样板文件/框架的一部分。它进一步扩展了try & catch的思想，例如使用回溯和异常进行错误处理(以及其他一些不错的特性)。
下面是负责try & catch的代码:
set -o pipefail
shopt -s expand_aliases
declare -ig __oo__insideTryCatch=0
# if try-catch is nested, then set +e before so the parent handler doesn't catch us
alias try="[[ \$__oo__insideTryCatch -gt 0 ]] && set +e;
__oo__insideTryCatch+=1; ( set -e;
trap \"Exception.Capture \${LINENO}; \" ERR;"
alias catch=" ); Exception.Extract \$? || "
Exception.Capture() {
local script="${BASH_SOURCE[1]#./}"
if [[ ! -f /tmp/stored_exception_source ]]; then
echo "$script" > /tmp/stored_exception_source
fi
if [[ ! -f /tmp/stored_exception_line ]]; then
echo "$1" > /tmp/stored_exception_line
fi
return 0
}
Exception.Extract() {
if [[ $__oo__insideTryCatch -gt 1 ]]
then
set -e
fi
__oo__insideTryCatch+=-1
__EXCEPTION_CATCH__=( $(Exception.GetLastException) )
local retVal=$1
if [[ $retVal -gt 0 ]]
then
# BACKWARDS COMPATIBILE WAY:
# export __EXCEPTION_SOURCE__="${__EXCEPTION_CATCH__[(${#__EXCEPTION_CATCH__[@]}-1)]}"
# export __EXCEPTION_LINE__="${__EXCEPTION_CATCH__[(${#__EXCEPTION_CATCH__[@]}-2)]}"
export __EXCEPTION_SOURCE__="${__EXCEPTION_CATCH__[-1]}"
export __EXCEPTION_LINE__="${__EXCEPTION_CATCH__[-2]}"
export __EXCEPTION__="${__EXCEPTION_CATCH__[@]:0:(${#__EXCEPTION_CATCH__[@]} - 2)}"
return 1 # so that we may continue with a "catch"
fi
}
Exception.GetLastException() {
if [[ -f /tmp/stored_exception ]] && [[ -f /tmp/stored_exception_line ]] && [[ -f /tmp/stored_exception_source ]]
then
cat /tmp/stored_exception
cat /tmp/stored_exception_line
cat /tmp/stored_exception_source
else
echo -e " \n${BASH_LINENO[1]}\n${BASH_SOURCE[2]#./}"
fi
rm -f /tmp/stored_exception /tmp/stored_exception_line /tmp/stored_exception_source
return 0
}
你可以自由使用，分叉和贡献——它在GitHub上。
另一种方法是简单地将命令与&&连接在一起，这样第一个失败的命令就会阻止其他命令的执行:
command1 &&
command2 &&
command3
这不是您在问题中要求的语法，但它是您所描述的用例的通用模式。一般来说，这些命令应该负责打印失败，这样您就不必手动执行了(当您不想要错误时，可以使用-q标志来屏蔽错误)。如果您有修改这些命令的能力，我会将它们编辑为在失败时大喊，而不是将它们包装在具有这种功能的其他东西中。
还要注意，你不需要这样做:
command1
if [ $? -ne 0 ]; then
你可以简单地说:
if ! command1; then
当你确实需要检查返回码时，使用算术上下文而不是[…]- ne:
ret=$?
# do something
if (( ret != 0 )); then
对于无意中发现这条线索的鱼壳用户。
假设foo是一个不“返回”(回显)值的函数，但它像往常一样设置退出码。 为了避免在调用函数后检查$status，你可以这样做:
foo; and echo success; or echo failure
如果它太长，不能放在一行上:
foo; and begin
echo success
end; or begin
echo failure
end
以功能的方式检查状态
assert_exit_status() {
lambda() {
local val_fd=$(echo $@ | tr -d ' ' | cut -d':' -f2)
local arg=$1
shift
shift
local cmd=$(echo $@ | xargs -E ':')
local val=$(cat $val_fd)
eval $arg=$val
eval $cmd
}
local lambda=$1
shift
eval $@
local ret=$?
$lambda : <(echo $ret)
}
用法:
assert_exit_status 'lambda status -> [[ $status -ne 0 ]] && echo Status is $status.' lls
输出
Status is 127
当我使用ssh时，我需要在errexit (set -e)模式下区分由连接问题和远程命令的错误代码引起的问题。我使用以下函数:
# prepare environment on calling site:
rssh="ssh -o ConnectionTimeout=5 -l root $remote_ip"
function exit255 {
local flags=$-
set +e
"$@"
local status=$?
set -$flags
if [[ $status == 255 ]]
then
exit 255
else
return $status
fi
}
export -f exit255
# callee:
set -e
set -o pipefail
[[ $rssh ]]
[[ $remote_ip ]]
[[ $( type -t exit255 ) == "function" ]]
rjournaldir="/var/log/journal"
if exit255 $rssh "[[ ! -d '$rjournaldir/' ]]"
then
$rssh "mkdir '$rjournaldir/'"
fi
rconf="/etc/systemd/journald.conf"
if [[ $( $rssh "grep '#Storage=auto' '$rconf'" ) ]]
then
$rssh "sed -i 's/#Storage=auto/Storage=persistent/' '$rconf'"
fi
$rssh systemctl reenable systemd-journald.service
$rssh systemctl is-enabled systemd-journald.service
$rssh systemctl restart systemd-journald.service
sleep 1
$rssh systemctl status systemd-journald.service
$rssh systemctl is-active systemd-journald.service
你可以在非redhat系统上使用@john-kugelman的解决方案，在他的代码中注释掉这一行:
. /etc/init.d/functions
然后，在最后粘贴下面的代码。完全披露:这只是从Centos 7中直接复制和粘贴上述文件的相关位。
在MacOS和Ubuntu 18.04上测试。
BOOTUP=color
RES_COL=60
MOVE_TO_COL="echo -en \\033[${RES_COL}G"
SETCOLOR_SUCCESS="echo -en \\033[1;32m"
SETCOLOR_FAILURE="echo -en \\033[1;31m"
SETCOLOR_WARNING="echo -en \\033[1;33m"
SETCOLOR_NORMAL="echo -en \\033[0;39m"
echo_success() {
[ "$BOOTUP" = "color" ] && $MOVE_TO_COL
echo -n "["
[ "$BOOTUP" = "color" ] && $SETCOLOR_SUCCESS
echo -n $" OK "
[ "$BOOTUP" = "color" ] && $SETCOLOR_NORMAL
echo -n "]"
echo -ne "\r"
return 0
}
echo_failure() {
[ "$BOOTUP" = "color" ] && $MOVE_TO_COL
echo -n "["
[ "$BOOTUP" = "color" ] && $SETCOLOR_FAILURE
echo -n $"FAILED"
[ "$BOOTUP" = "color" ] && $SETCOLOR_NORMAL
echo -n "]"
echo -ne "\r"
return 1
}
echo_passed() {
[ "$BOOTUP" = "color" ] && $MOVE_TO_COL
echo -n "["
[ "$BOOTUP" = "color" ] && $SETCOLOR_WARNING
echo -n $"PASSED"
[ "$BOOTUP" = "color" ] && $SETCOLOR_NORMAL
echo -n "]"
echo -ne "\r"
return 1
}
echo_warning() {
[ "$BOOTUP" = "color" ] && $MOVE_TO_COL
echo -n "["
[ "$BOOTUP" = "color" ] && $SETCOLOR_WARNING
echo -n $"WARNING"
[ "$BOOTUP" = "color" ] && $SETCOLOR_NORMAL
echo -n "]"
echo -ne "\r"
return 1
}
假设
alias command1='grep a <<<abc'
alias command2='grep x <<<abc'
alias command3='grep c <<<abc'
要么
{ command1 1>/dev/null || { echo "cmd1 fail"; /bin/false; } } && echo "cmd1 succeed" &&
{ command2 1>/dev/null || { echo "cmd2 fail"; /bin/false; } } && echo "cmd2 succeed" &&
{ command3 1>/dev/null || { echo "cmd3 fail"; /bin/false; } } && echo "cmd3 succeed"
or
{ { command1 1>/dev/null && echo "cmd1 succeed"; } || { echo "cmd1 fail"; /bin/false; } } &&
{ { command2 1>/dev/null && echo "cmd2 succeed"; } || { echo "cmd2 fail"; /bin/false; } } &&
{ { command3 1>/dev/null && echo "cmd3 succeed"; } || { echo "cmd3 fail"; /bin/false; } }
收益率
cmd1 succeed
cmd2 fail
这是乏味的。但是可读性还不错。
