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。
当前回答
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
其他回答
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。
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
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。
run() {
$*
if [ $? -ne 0 ]
then
echo "$* failed with exit code $?"
return 1
else
return 0
fi
}
run command1 && run command2 && run command3
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。
