Unix/Linux腳本中“set -e”的作用
-----------------------------------------------------------
#!/bin/bash
set -e
command 1
command 2
...
exit 0
----------------------------------------------------------
Every script you write should include set -e at the top. This tells bash that it should exit the script if any statement returns a non-true return value. The benefit of using -e is that it prevents errors snowballing into serious issues when they could have been caught earlier. Again, for readability you may want to use set -o errexit.
你寫的每個腳本都應該在文件開頭加上set -e,這句語句告訴bash如果任何語句的執行結果不是true則應該退出。這樣的好處是防止錯誤像滾雪球般變大導致一個致命的錯誤，而這些錯誤本應該在之前就被處理掉。如果要增加可讀性，可以使用set -o errexit，它的作用與set -e相同。
Using -e gives you error checking for free. If you forget to check something, bash will do it for you. Unfortunately it means you can't check $? as bash will never get to the checking code if it isn't zero. There are other constructs you could use:
使用-e幫助你檢查錯誤。如果你忘記檢查（執行語句的結果），bash會幫你執行。不幸的是，你將無法檢查$?，因為如果執行的語句不是返回0，bash將無法執行到檢查的代碼。你可以使用其他的結構：
[plain]
command
if [ "$?"-ne 0]; then
echo "command failed";
exit 1;
fi
could be replaced with
能夠被代替為
[plain]
command || { echo "command failed"; exit 1; }
or
或者
[plain]
if ! command; then
echo "command failed";
exit 1;
fi
What if you have a command that returns non-zero or you are not interested in its return value? You can use command || true, or if you have a longer section of code, you can turn off the error checking, but I recommend you use this sparingly.
如果你有一個命令返回非0或者你對語句執行的結果不關心，那你可以使用command || true，或者你有一段很長的代碼，你可以關閉錯誤檢查（不使用set -e），但是我還是建議你保守地使用這個語句。
