如何验证文件是否未传入

Question

所以我有一个脚本，它从用户那里获取带有选项-y或-n的文件，并且需要-d脚本运行/example.sh-d文件-y或-n可变

file=""

如果用户没有在例如中传递文件，我需要进行验证

./example.sh -y       --- it should give error "must provide file"`
./example.sh -n       --- it should give error "must provide file"`
./example.sh -d       --- it should give error "must provide file"
./example.sh -y -n       --- it should give error "must provide file"

我想出了这个，但没用#检查文件是否提供

if [ $file -eq 1 ]; then
echo "No file provided"
exit 1
fi

# Does the file exist 
which works for checking if the file exists but it only check if the file in there
if [[ ! -f $file ]]; then
echo
echo "Error: The file $file does not exist."
exit 1
fi

Answer 1

为什么不简单地循环参数并测试case语句中的-d、-n和-y选项呢。根据我的理解，文件名必须跟在-d选项后面。在case语句中处理-d选项时，请检查下一个参数是否包含系统中存在的非空文件名，如果是，请设置文件名，例如filename="${argv[i+1]}"。

当您退出选项处理循环时，只需测试是否设置了filename，即可得到答案。

一个简短的例子可能是：

#!/bin/bash
argc=$#         ## argument count
argv=("$@")     ## array holding arguments (argument vector)
filename=       ## filename is empty
## loop over all arguments, filename must follow -d 
for ((i = 0; i < argc; i++)); do
case "${argv[i]}" in
## file exists and non-empty, set filename to argument
-d ) [ -s "${argv[i+1]}" ] && { filename="${argv[i+1]}"; };;
-n ) # do whatever for option n
;;
-y ) # do whatever for option y
;;
esac
done
[ -n "$filename" ] || {   ## check filename set or exit
printf "error: file empty or not readable.n" >&2
exit 1
}
## valid filename received
printf "file '%s' found - script running.n" "$filename"

只有在-d选项之后提供了有效的文件名，脚本才会运行。否则，它将给出一条错误消息并退出。

示例

$ ./process-opts.sh -y -n
error: file empty or not readable.

或

$ ./process-opts.sh -y -d -n
error: file empty or not readable.

最后

$ ./process-opts.sh -y -d README -n
file 'README' found - script running.

或按任何顺序：

$ ./process-opts.sh -y -n -d README
file 'README' found - script running.