bash Shell 脚本中的布尔表达式
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/48774/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Boolean Expressions in Shell Scripts
提问by Adam Ernst
What's the "right" way to do the following as a boolean expression?
作为布尔表达式执行以下操作的“正确”方法是什么？
for i in `ls /resources`; do
if [ $i != "database.db" ]
then
if [ $i != "tiles" ]
then
if [ $i != "map.pdf" ]
then
if [ $i != "map.png" ]
then
svn export -q /resources/$i ../MyProject/Resources/$i
...
采纳答案by pixelbeat
The other solutions have a couple of common mistakes: http://www.pixelbeat.org/programming/shell_script_mistakes.html
其他解决方案有几个常见的错误：http: //www.pixelbeat.org/programming/shell_script_mistakes.html
for i in $(ls ...)is redundant/problematic just do:for i in $1/resources*; do ...[ $i != file1 -a $1 != file2 ]This actually has 2 problems.a. The
$iis not quoted, hence names with spaces will cause issuesb.
-ais inefficient ifstating files as it doesn't short circuit (I know the above is notstating files).
for i in $(ls ...)是多余的/有问题的只是做：for i in $1/resources*; do ...[ $i != file1 -a $1 != file2 ]这实际上有两个问题。一种。在
$i没有加引号，因此用空格会导致一些问题名湾
-a如果stating 文件没有短路，则效率低下（我知道上面不是stating 文件）。
So instead try:
因此，请尝试：
for i in /resources/*; do
if [ "$i" != "database.db" ] &&
[ "$i" != "tiles" ] &&
[ "$i" != "map.pdf" ] &&
[ "$i" != "map.png" ]; then
svn export -q "$i" "../MyProject/Resources/$(basename $i)"
fi
done
回答by Mo.
Even shorter:
更短：
for i in `ls /resources`; do
if [ $i != databse.db -a $i != titles -a $i != map.pdf ]; then
svn export -q /resources/$i ../MyProject/Resources/$i
fi
done;
The -ain the if expression is the equivalent of the boolean AND in shell-tests. For more see man test
的-a在if表达式是等效的布尔AND在壳测试。更多见man test
回答by Fred Yankowski
Consider using a casestatement:
考虑使用case语句：
for i in $(ls /resources); do
case $i in
database.db|tiles|map.pdf|map.png)
;;
*)
svn export -q /resources/$i ../MyProject/Resources/$i;;
esac
done
回答by frizz
for i in `ls /resources`; do
if [ $i != "database.db" ] && [ $i != "tiles" ] && [ $i != "map.pdf" ] && [ $i != "map.png" ]; then
svn export -q /resources/$i ../MyProject/Resources/$i
回答by Evan Langlois
For future reference, the new [[ test operator is preferred. The accepted answer is close and everything mentioned applies, but that answer will require lots of quoting and calls to multiple tests.
为了将来参考，首选新的 [[ 测试运算符。接受的答案很接近，提到的所有内容都适用，但该答案需要大量引用和调用多个测试。
The preferred method would be something like:
首选方法类似于：
for i in /resources/*; do
if [[ $i != "database.db" && $i != "tiles" &&
$i != "map.pdf" && $i != "map.png" ]]; then
svn export -q "$i" "../MyProject/Resources/$(basename $i)"
fi
done
