keakons-MacBook-Pro:test keakon$ touch "test 1"
keakons-MacBook-Pro:test keakon$ touch "test 2"
keakons-MacBook-Pro:test keakon$ touch "test 3"
keakons-MacBook-Pro:test keakon$ ls
test 1 test 2 test 3

然后for循環(huán)輸出文件名：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ for file in `ls`;
> do echo $file;
> done
test
1
test
2
test
3

可以看到，文件名被分開(kāi)了。

復(fù)制操作也不行：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ mkdir ../bak
keakons-MacBook-Pro:test keakon$ for file in `ls`; do cp "$file" ../bak; done
cp: bak is a directory (not copied).
cp: test: No such file or directory
cp: 1: No such file or directory
cp: test: No such file or directory
cp: 2: No such file or directory
cp: test: No such file or directory
cp: 3: No such file or directory

要解決這個(gè)問(wèn)題，當(dāng)然就要從單詞分隔符著手。而bash中使用的是$IFS（Internal Field Separator）這個(gè)變量，內(nèi)容為" \n\t"：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ echo $IFS

keakons-MacBook-Pro:test keakon$ echo "$IFS" | od -t x1
0000000 20 09 0a 0a
0000004
keakons-MacBook-Pro:test keakon$ echo "" | od -t x1
0000000 0a
0000001

然后把它改成"\n\b"，記得修改前先保存一下：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ SAVEIFS=$IFS
keakons-MacBook-Pro:test keakon$ IFS=$(echo -en "\n\b")

現(xiàn)在再執(zhí)行上述命令就正常了：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ for file in `ls`; do echo $file; done
test 1
test 2
test 3
keakons-MacBook-Pro:test keakon$ for file in `ls`; do cp "$file" ../bak; done
keakons-MacBook-Pro:test keakon$ ls ../bak
test 1 test 2 test 3

最后，別忘了恢復(fù)$IFS：

復(fù)制代碼代碼如下:

keakons-MacBook-Pro:test keakon$ IFS=$SAVEIFS
keakons-MacBook-Pro:test keakon$ echo "$IFS" | od -t x1
0000000    20  09  0a  0a                                                
0000004
keakons-MacBook-Pro:test keakon$ IFS=$(echo -en " \n\t")
keakons-MacBook-Pro:test keakon$ echo "$IFS" | od -t x1
0000000    20  0a  09  0a                                                
0000004