我正在写一个shell脚本,需要检查终端应用程序是否已安装。我想使用TRY/CATCH命令来做到这一点,除非有更整洁的方法。
当前回答
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。
其他回答
你有陷阱http://www.tldp.org/LDP/Bash-Beginners-Guide/html/sect_12_02.html,这是不一样的,但你可以使用其他技术来达到这个目的
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${BASH_SOURCE[2]#./}"
fi
rm -f /tmp/stored_exception /tmp/stored_exception_line /tmp/stored_exception_source
return 0
}
你可以自由使用,分叉和贡献——它在GitHub上。
假设终端应用名为'app'(你希望它在你的$PATH中):
if [[ ! `which app` ]]; then
# run code if app not installed
else
# run code if app is installed
fi
你可以:
#!/bin/bash
if <command> ; then # TRY
<do-whatever-you-want>
else # CATCH
echo 'Exception'
<do-whatever-you-want>
fi
我使用的方法是这样的:
YOUR COMMAND HERE
EXITCODE=$?
if [ "$EXITCODE" -ne "0" ]; then
#this is the catch part
echo "uh oh"
exit $EXITCODE
fi
这只是检查命令的退出码,并将其与零进行比较 (表示命令运行成功)