#Bash 的 sed 命令

sed [OPTION]... SCRIPT [FILE]...

功能

用于过滤和转换文本的流式编辑器。

类型

可执行文件（/usr/bin/sed）。

参数

OPTION 选项：
- -n, --quiet, --silent - 不自动输出；默认打印所有行，开启此选项则只打印 p 命令匹配的行
- --debug - 打印执行过程
- -e script, --expression=script - 指定处理脚本；可多次使用此选项传递多个处理脚本
- -f script-file, --file=script-file - 从 script-file 中读取处理脚本
- --follow-symlinks - 修改文件时跟踪符号链接
- -i[SUFFIX], --in-place[=SUFFIX] - 修改原文件；如果指定了 SUFFIX，则写入添加了后缀 SUFFIX 的文件
- -l N, --line-length=N - 为 l 命令指定所需的换行长度
- --posix - 禁用 GNU 扩展
- -E, -r, --regexp-extended - 处理脚本中使用扩展正则表达式
- -s, --separate - 将文件视为独立的，而非单一连续的长流
- --sandbox - 以沙盒模式运行（禁用 e r w 模式）
- -u, --unbuffered - 从输入文件中加载最少量的数据，并更频繁的更新输出
- -z, --null-data - 以空字符（\0）作为行的结尾，而不是换行符（\n）
- --help - 显示帮助
- --version - 显示版本
SCRIPT - 处理脚本
FILE - 输入文件，省略此参数或将此参数设为 - 则读取标准输入

#脚本命令

命令	含义
s	替换
d	删除
p	打印
a	追加
i	插入
c	替换整行
y	字符转换
r	读取文件
w	写入文件

详见示例

#正则表达式

sed 主要支持两种风格的正则：基本正则 (BRE - Basic Regular Expression) 和 扩展正则 (ERE - Extended Regular Expression)。

核心差异对比

特性	基本正则 (BRE)	扩展正则 (ERE)
选项	无 (默认)	`-E`
次数匹配 `{n,m}`	`\{n,m\}`	`{n,m}`
分组 `()`	`\(\)`	`()`
或运算 `\|`	`\\|`	`\|`
1次或多次 `+`	`\+`	`+`
0次或1次 `?`	`\?`	`?`
预定义类 (如 \d)	不支持	不支持
非贪婪匹配	不支持	不支持

#基本正则表达式

这是 grep 默认使用的模式。它的原则是“尽量把字符当成普通文本”，因此很多特殊元字符需要通过反斜杠 \ 转义后才具有特殊含义。

?, +, {, |, (, ) 这些符号在 BRE 中被视为普通字符。
如果要使用它们的正则功能，必须转义：\?, \+, \{, \|, \(。

#扩展正则表达式

ERE 简化了语法，去掉了大部分反斜杠。它认为这些特殊符号“天生”就应该是功能符号。

使用 -E 选项开启
?, +, {, |, (, ) 直接作为正则的元字符使用，无需转义。
如果要将它们当作普通字符，必须转义：\?, \+, \{, \|, \(。

#示例

打印(p)

$ sed -n '1,3p' file.txt                # 打印 1 至 3行
$ sed -n '/error/p' file.txt            # 打印包含 error 的行

-n 选项表示只打印 p 匹配的行

替换(s)

$ sed 's/http/https/' file.txt          # 将每行第一个 http 替换为 https
$ sed 's/http/https/g' file.txt         # 将所有 http 替换为 https
$ sed '3s/http/https/' file.txt         # 将第 3 行第一个 http 替换为 https
$ sed '3s/http/https/g' file.txt        # 将第 3 行所有 http 替换为 https

上述命令将修改后的内容打印到标准输出，而不修改源文件
添加 -i 选项则会修改源文件
末尾的 g 表示全局模式

整行替换(c)

$ sed '2c \xplanc.org' file.txt         # 将第二行替换为 xplanc.org
$ sed '2,4c \xplanc.org' file.txt       # 将 2 至 4 行合并为一行并替换为 xplanc.org
$ sed '/TODO/2c \xplanc.org' file.txt   # 将 TODO 匹配的行整行替换为 xplanc.org

上述命令将修改后的内容打印到标准输出，而不修改源文件
添加 -i 选项则会修改源文件

转换(y)

$ sed 'y/123/abc/' file.txt             # 将所有的 1 替换为 a，2 替换为  b，3 替换为 c

上述命令将修改后的内容打印到标准输出，而不修改源文件
添加 -i 选项则会修改源文件

删除(d)

$ sed '2d' file.txt                     # 删除第 2 行
$ sed '2,4d' file.txt                   # 删除 2 到 4 行
$ sed '$d' file.txt                     # 删除最后一行
$ sed '7,$d' file.txt                   # 删除 7 到最后一行

上述命令将修改后的内容打印到标准输出，而不修改源文件
添加 -i 选项则会修改源文件

追加(a)

$ sed '2a \Hello' file.txt              # 在第 2 行后追加   
$ sed '$a \Hello' file.txt              # 在最后一行后追加   
$ sed '/Linux/a \Hello' file.txt        # 在 Linux 匹配的行之后追加

上述命令将修改后的内容打印到标准输出，而不修改源文件
添加 -i 选项则会修改源文件

行号定位

$ sed -n '5p' file.txt                 # 第 5 行
$ sed -n '1,3p' file.txt               # 第 1 到 3 行
$ sed -n '5,$p' file.txt               # 第 5 行到最后
$ sed -n '1~2p' file.txt               # 奇数行（从第 1 行开始每隔 2 行）
$ sed -n '2~3p' file.txt               # 从第 2 行开始每隔 3 行

-n 选项表示只打印 p 匹配的行

正则定位

$ sed -n '/^root/p' file.txt           # 以 root 开头的行
$ sed -n '/bash$/p' file.txt           # 以 bash 结尾的行
$ sed -n '/error/!p' file.txt          # 不包含 error 的行
$ sed -n '/start/,/end/p' file.txt     # 从包含 start 的行到包含 end 的行

-n 选项表示只打印 p 匹配的行

混合定位

$ sed -n '1,/error/' file.txt          # 从第 1 行到包含 error 的行
$ sed -n '/error/,20' file.txt         # 从包含 error 的行到第 20 行
$ sed -n '/start/,/end/p' file.txt     # 从包含 start 的行到包含 end 的行

-n 选项表示只打印 p 匹配的行

混合命令

$ sed -n 's/http/https/gp' file.txt    # 将所有 http 替换为 https，并且只打印匹配的行

s 表示替换、g 表示全局模式、p 表示打印
-n 选项表示只打印 p 匹配的行

#推荐阅读

sed(1) — Linux manual page

#手册

SED(1)                           User Commands                          SED(1)

NAME
       sed - stream editor for filtering and transforming text

SYNOPSIS
       sed [-V] [--version] [--help] [-n] [--quiet] [--silent]
           [-l N] [--line-length=N] [-u] [--unbuffered]
           [-E] [-r] [--regexp-extended]
           [-e script] [--expression=script]
           [-f script-file] [--file=script-file]
           [script-if-no-other-script]
           [file...]

DESCRIPTION
       Sed  is a stream editor.  A stream editor is used to perform basic text
       transformations on an input stream (a file or input from  a  pipeline).
       While  in  some  ways similar to an editor which permits scripted edits
       (such as ed), sed works by making only one pass over the input(s),  and
       is consequently more efficient.  But it is sed's ability to filter text
       in  a  pipeline which particularly distinguishes it from other types of
       editors.

       -n, --quiet, --silent

              suppress automatic printing of pattern space

       --debug

              annotate program execution

       -e script, --expression=script

              add the script to the commands to be executed

       -f script-file, --file=script-file

              add the contents of script-file to the commands to be executed

       --follow-symlinks

              follow symlinks when processing in place

       -i[SUFFIX], --in-place[=SUFFIX]

              edit files in place (makes backup if SUFFIX supplied)

       -l N, --line-length=N

              specify the desired line-wrap length for the `l' command

       --posix

              disable all GNU extensions.

       -E, -r, --regexp-extended

              use extended regular expressions in the script (for  portability
              use POSIX -E).

       -s, --separate

              consider  files  as separate rather than as a single, continuous
              long stream.

       --sandbox

              operate in sandbox mode (disable e/r/w commands).

       -u, --unbuffered

              load minimal amounts of data from the input files and flush  the
              output buffers more often

       -z, --null-data

              separate lines by NUL characters

       --help
              display this help and exit

       --version
              output version information and exit

       If  no  -e, --expression, -f, or --file option is given, then the first
       non-option argument is taken as the sed script to interpret.   All  re‐
       maining arguments are names of input files; if no input files are spec‐
       ified, then the standard input is read.

       GNU  sed  home page: <https://www.gnu.org/software/sed/>.  General help
       using GNU software: <https://www.gnu.org/gethelp/>.  E-mail bug reports
       to: <bug-sed@gnu.org>.

       Packaged by Debian Copyright © 2022 Free Software Foundation, Inc.  Li‐
       cense  GPLv3+:  GNU  GPL  version  3  or   later   <https://gnu.org/li‐
       censes/gpl.html>.   This  is  free software: you are free to change and
       redistribute it.  There is NO WARRANTY, to the extent permitted by law.

COMMAND SYNOPSIS
       This is just a brief synopsis of sed commands to serve as a reminder to
       those who already know sed; other documentation (such  as  the  texinfo
       document) must be consulted for fuller descriptions.

   Zero-address ``commands''
       : label
              Label for b and t commands.

       #comment
              The  comment  extends until the next newline (or the end of a -e
              script fragment).

       }      The closing bracket of a { } block.

   Zero- or One- address commands
       =      Print the current line number.

       a \

       text   Append text, which has each embedded newline preceded by a back‐
              slash.

       i \

       text   Insert text, which has each embedded newline preceded by a back‐
              slash.

       q [exit-code]
              Immediately quit the sed script without processing any more  in‐
              put,  except that if auto-print is not disabled the current pat‐
              tern space will be printed.  The exit code argument is a GNU ex‐
              tension.

       Q [exit-code]
              Immediately quit the sed script without processing any more  in‐
              put.  This is a GNU extension.

       r filename
              Append text read from filename.

       R filename
              Append  a  line read from filename.  Each invocation of the com‐
              mand reads a line from the file.  This is a GNU extension.

   Commands which accept address ranges
       {      Begin a block of commands (end with a }).

       b label
              Branch to label; if label is omitted, branch to end of script.

       c \

       text   Replace the selected lines with text, which  has  each  embedded
              newline preceded by a backslash.

       d      Delete pattern space.  Start next cycle.

       D      If  pattern  space contains no newline, start a normal new cycle
              as if the d command was issued.  Otherwise, delete text  in  the
              pattern  space  up  to the first newline, and restart cycle with
              the resultant pattern space, without reading a new line  of  in‐
              put.

       h H    Copy/append pattern space to hold space.

       g G    Copy/append hold space to pattern space.

       l      List out the current line in a ``visually unambiguous'' form.

       l width
              List  out  the  current line in a ``visually unambiguous'' form,
              breaking it at width characters.  This is a GNU extension.

       n N    Read/append the next line of input into the pattern space.

       p      Print the current pattern space.

       P      Print up to the first embedded newline of  the  current  pattern
              space.

       s/regexp/replacement/
              Attempt  to match regexp against the pattern space.  If success‐
              ful, replace that portion matched  with  replacement.   The  re‐
              placement  may  contain the special character & to refer to that
              portion of the pattern space which matched, and the special  es‐
              capes  \1 through \9 to refer to the corresponding matching sub-
              expressions in the regexp.

       t label
              If a s/// has done a successful substitution since the last  in‐
              put line was read and since the last t or T command, then branch
              to label; if label is omitted, branch to end of script.

       T label
              If no s/// has done a successful substitution since the last in‐
              put line was read and since the last t or T command, then branch
              to label; if label is omitted, branch to end of script.  This is
              a GNU extension.

       w filename
              Write the current pattern space to filename.

       W filename
              Write  the  first line of the current pattern space to filename.
              This is a GNU extension.

       x      Exchange the contents of the hold and pattern spaces.

       y/source/dest/
              Transliterate the characters in the pattern space  which  appear
              in source to the corresponding character in dest.

Addresses
       Sed  commands can be given with no addresses, in which case the command
       will be executed for all input lines; with one address, in  which  case
       the  command will only be executed for input lines which match that ad‐
       dress; or with two addresses, in which case the command  will  be  exe‐
       cuted  for  all  input  lines  which match the inclusive range of lines
       starting from the first address and continuing to the  second  address.
       Three  things  to  note about address ranges: the syntax is addr1,addr2
       (i.e., the addresses are separated by a comma); the  line  which  addr1
       matched will always be accepted, even if addr2 selects an earlier line;
       and  if  addr2 is a regexp, it will not be tested against the line that
       addr1 matched.

       After the address (or address-range), and before the command, a !   may
       be inserted, which specifies that the command shall only be executed if
       the address (or address-range) does not match.

       The following address types are supported:

       number Match  only  the specified line number (which increments cumula‐
              tively across files, unless the -s option is  specified  on  the
              command line).

       first~step
              Match every step'th line starting with line first.  For example,
              ``sed -n 1~2p'' will print all the odd-numbered lines in the in‐
              put  stream,  and  the  address 2~5 will match every fifth line,
              starting with the second.  first can be zero; in this case,  sed
              operates as if it were equal to step.  (This is an extension.)

       $      Match the last line.

       /regexp/
              Match lines matching the regular expression regexp.  Matching is
              performed  on  the  current pattern space, which can be modified
              with commands such as ``s///''.

       \cregexpc
              Match lines matching the regular expression regexp.  The  c  may
              be any character.

       GNU sed also supports some special 2-address forms:

       0,addr2
              Start  out  in  "matched  first  address"  state, until addr2 is
              found.  This is similar to 1,addr2, except that if addr2 matches
              the very first line of input the 0,addr2 form will be at the end
              of its range, whereas the 1,addr2 form will still be at the  be‐
              ginning  of  its range.  This works only when addr2 is a regular
              expression.

       addr1,+N
              Will match addr1 and the N lines following addr1.

       addr1,~N
              Will match addr1 and the lines following addr1  until  the  next
              line whose input line number is a multiple of N.

REGULAR EXPRESSIONS
       POSIX.2 BREs should be supported, but they aren't completely because of
       performance  problems.  The \n sequence in a regular expression matches
       the newline character, and similarly for \a, \t, and  other  sequences.
       The  -E  option switches to using extended regular expressions instead;
       it has been supported for years by GNU sed,  and  is  now  included  in
       POSIX.

BUGS
       E-mail bug reports to bug-sed@gnu.org.  Also, please include the output
       of ``sed --version'' in the body of your report if at all possible.

AUTHOR
       Written by Jay Fenlason, Tom Lord, Ken Pizzini, Paolo Bonzini, Jim Mey‐
       ering, and Assaf Gordon.

       This  sed  program was built with SELinux support.  SELinux is disabled
       on this system.

       GNU sed home page: <https://www.gnu.org/software/sed/>.   General  help
       using GNU software: <https://www.gnu.org/gethelp/>.  E-mail bug reports
       to: <bug-sed@gnu.org>.

SEE ALSO
       awk(1),  ed(1),  grep(1),  tr(1),  perlre(1),  sed.info, any of various
       books on sed, the sed FAQ (http://sed.sf.net/grabbag/tutorials/sed‐
       faq.txt), http://sed.sf.net/grabbag/.

       The full documentation for sed is maintained as a Texinfo manual.  If
       the info and sed programs are properly installed at your site, the com‐
       mand

              info sed

       should give you access to the complete manual.

GNU sed 4.9                       April 2024                            SED(1)

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