Linux 带有 -i 选项（就地编辑）的 sed 命令在 Ubuntu 上工作正常，但在 Mac 上不工作

sed command with -i option (in-place editing) works fine on Ubuntu but not Mac

提问by Michelle Williamson

I know nothing about Sed but need this command (which works fine on Ubuntu) to work on a Mac OSX:

我对 Sed 一无所知，但需要此命令（在 Ubuntu 上运行良好）才能在 Mac OSX 上运行：

sed -i "/ $domain .*#drupalpro/d" /etc/hosts

I'm getting:

我越来越：

sed: 1: "/etc/hosts": extra characters at the end of h command

回答by Diego Torres Milano

man is your friend.

男人是你的朋友。

OS X

操作系统

 -i extension
         Edit files in-place, saving backups with the specified extension.
         If a zero-length extension is given, no backup will be saved.  It
         is not recommended to give a zero-length extension when in-place
         editing files, as you risk corruption or partial content in situ-
         ations where disk space is exhausted, etc.

回答by microtherion

Ubuntu ships with GNU sed, where the suffix for the -ioption is optional. OS X ships with BSD sed, where the suffix is mandatory. Try sed -i ''

Ubuntu 附带 GNU sed，其中-i选项的后缀是可选的。OS X 附带 BSD sed，其中后缀是强制性的。尝试sed -i ''

回答by jcarballo

In OS X, you can use the GNU version of sed: gsed.

在 OS X 中，您可以使用 sed: 的 GNU 版本gsed。

# if using brew
brew install gnu-sed

#if using ports
sudo port install gsed

Then, if your script should be portable, depending on your OS you can define which command to use.

然后，如果您的脚本应该是可移植的，则根据您的操作系统，您可以定义要使用的命令。

SED=sed
unamestr=`uname`
if [[ "$unamestr" == "Darwin" ]] ; then
    SED=gsed
    type $SED >/dev/null 2>&1 || {
        echo >&2 "$SED it's not installed. Try: brew install gnu-sed" ;
        exit 1;
    }
fi
# here your sed command, e.g.:
$SED -i "/ $domain .*#drupalpro/d" /etc/hosts

回答by mklement0

To complement microtherion's helpful, to-the-point answer:

为了补充microtherion 有用的、直截了当的答案：

• with a portable solution
• with background information

• 使用便携式解决方案
• 有背景资料

tl;dr:

tl;博士：

The equivalent of this GNUsed(standard on most Linuxdistros) command:

相当于这个GNUsed（大多数Linux发行版的标准）命令：

sed -i    's/foo/bar/' file

is this BSD/macOSsedcommand:

这是BSD/macOSsed命令：

sed -i '' 's/foo/bar/' file  # Note the '' as a *separate argument*

With BSD/macOSsed, the following commands do notworkat all or not as intended:

随着BSD / MacOS的sed，下面的命令做不工作在所有或不按预期：

sed -i    's/foo/bar/' file  # Breaks; script is misinterpreted as backup-file suffix
sed -i''  's/foo/bar/' file  # Ditto
sed -i -e 's/foo/bar/' file  # -e is misinterpreted as backup-file suffix

For a discussion of allthe differences between GNU sedand BSD/macOS sed, see this answerof mine.

有关GNU和 BSD/macOS之间所有差异的讨论，请参阅我的这个答案。sedsed

Portable approach:

便携式方法：

^{Note: Portablehere means that the command works with both implementations discussed. It is not portable in a POSIXsense, because the -ioption is not POSIX-compliant.}

^{注意：此处的可移植意味着该命令适用于所讨论的两种实现。它在POSIX意义上是不可移植的，因为该-i选项不符合 POSIX 标准。}

# Works with both GNU and BSD/macOS Sed, due to a *non-empty* option-argument:
# Create a backup file *temporarily* and remove it on success.
sed -i.bak 's/foo/bar/' file && rm file.bak

For an explanation, see below; for alternative solutions, including a POSIX-compliant one, see this related answerof mine.

有关解释，请参见下文；对于替代解决方案，包括符合 POSIX 标准的解决方案，请参阅我的这个相关答案。

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Background information

背景资料

In GNUsed(standard on most Linux distros) and BSD/macOSsed, the -ioption, which performs in-place updating^[1]of its input files, accepts an option-argumentthat specifies what suffix(filename extension) to use for the backup fileof the file being updated.

在GNUsed（在大多数Linux发行版标准）和BSD / MACOSsed，该-i选项，该选项进行就地更新^[1]的其输入文件，接受一个选项形式参数，以指定后缀（文件扩展名），以用于该备份文件正在更新的文件。

E.g., in bothimplementations, the following keeps the original file, file, as backup file file.bak:

例如，在这两种实现中，以下将原始文件file, 作为备份文件file.bak：

sed -i.bak 's/foo/bar/' file  # Keep original as 'file.bak'; NO SPACE between -i and .bak

Even though with GNUsedthe suffix argument is optional, whereas with BSD/macOSsedit is mandatory, the above syntax works with bothimplementations, because directly adjoining the option-argument (.bak) to the option (-i) - -i.bak, as opposed to -i .bak- works both as an optionaland a mandatoryoption-argument:

即使对于GNUsed后缀参数是optional，而对于BSD/macOSsed它是强制性的，上述语法适用于两种实现，因为直接将选项参数 ( .bak) 连接到选项 ( -i) - -i.bak，而不是-i .bak- 两者都可以作为一个可选的和一个强制性的选项参数：

• Syntax -i.bakis the onlyform that works for an optionaloption-argument.
• Syntax -i.bakalsoworks as a mandatoryoption-argument, as an alternativeto -i .bak, i.e., specifying the option and its argument separately.

• 语法-i.bak是唯一适用于可选选项参数的形式。
• 语法-i.bak也可以作为一个强制性的选项参数，作为一个替代方案，以-i .bak，即，指定选项及其参数分别。

Not specifying a suffix- which is often the case - means that no backup fileshould be kept, and that is where the incompatibility arises:

不指定后缀- 通常是这种情况 - 意味着不应该保留备份文件，这就是不兼容的地方：

• With GNUsed, not specifying a suffix means simply using -iby itself.

• With BSD/macOSsed, not specifying a suffix means specifying the empty stringas the - mandatory - suffix, and for technicalreasons, the empty string can only be passed as a separateargument: that is, -i ''not-i''.

• 随着GNUsed，只需使用不指定后缀手段-i本身。

• 对于BSD/macOSsed，不指定后缀意味着将空字符串指定为 - 强制 - 后缀，并且出于技术原因，空字符串只能作为单独的参数传递：即-i ''not-i''。

-i''doesn't work, because to sedit is indistinguishable from just -i, because the shelleffectively removesthe empty quotes (it concatenates -iand ''and removes quotes with syntactical function), and passes just -iin bothcases.

-i''不工作，因为sed它是从仅仅区分-i，因为外壳有效地消除了空引号（它加到-i和''与句法功能可以去除引号），只传递-i在这两种情况下。

With (effectively) just -ispecified, it is the nextargument that is interpreted as the option-argument:

通过（有效地）刚刚-i指定，下一个参数被解释为选项参数：

sed -i 's/foo/bar/' file # BREAKS with BSD/macOS Sed

's/foo/bar/'- intended to the the Sed script(command) - is now interpreted as the suffix, and the word fileis interpreted as the script.
Interpreting such a word as script then leads to obscure error message such as
sed: 1: "file": invalid command code f,
because the fis interpreted as a Sed command (function).

's/foo/bar/'- 用于 Sed脚本（命令） - 现在被解释为后缀，并且单词file被解释为脚本。
将这样的单词解释为 script 然后会导致模糊的错误消息，例如
sed: 1: "file": invalid command code f，
因为f被解释为 Sed 命令（函数）。

Similarly, with:

同样，与：

sed -i -e 's/foo/bar/' file # CREATES BACKUP FILE 'file-e'

-eis interpreted as the suffixargument, and NOT as Sed's -eoption(which can be used to specify multiplecommands, if needed).
As as result, instead of keeping NO backup, you get a backup file with suffix -e.

-e被解释为后缀参数，而不是 Sed 的-e选项（如果需要，可用于指定多个命令）。
因此，您将获得一个后缀为-e.

That this command doesn't work as intended is less obvious, because the in-place updating does succeed, given that the syntax requirement of the suffix argument is satisfied by the -eargument.

这个命令没有按预期工作不太明显，因为就地更新确实成功了，因为参数满足了后缀参数的语法要求-e。

That the accidental creation of these backup files easily goes unnoticed is the likeliest explanation for Crt's incorrect answerand this incorrect answer to a similar questionhaving received so many up-votes (as of this writing).

这些备份文件的意外创建很容易被忽视，这是对Crt 错误答案的最可能解释，而这个对类似问题的错误答案已经收到了如此多的赞成票（在撰写本文时）。

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^{[1] Strictly speaking, a temporary file is created behind the scenes that then replacesthe original file; this approach can be problematic: see the bottom half of this answerof mine.}

^{[1] 严格来说，是在后台创建一个临时文件，然后替换原来的文件；这种方法可能有问题：请参阅我的这个答案的下半部分。}