使用sed，最简单的语法:

sed \
    -e '/^\(option=\).*/{s//\1value/;:a;n;ba;q}' \
    -e '$aoption=value' filename

如果参数存在，这将替换它，否则将把它添加到文件的底部。

如果您想就地编辑文件，请使用-i选项。

如果你想接受并保留空白，并且除了删除注释之外，如果行已经存在，但被注释掉了，那么写:

sed -i \
    -e '/^#\?\(\s*option\s*=\s*\).*/{s//\1value/;:a;n;ba;q}' \
    -e '$aoption=value' filename

请注意，选项和值都不能包含斜杠/，否则必须将其转义为\/。

要使用bash变量$option和$value，你可以这样写:

sed -i \
    -e '/^#\?\(\s*'${option//\//\\/}'\s*=\s*\).*/{s//\1'${value//\//\\/}'/;:a;n;ba;q}' \
    -e '$a'${option//\//\\/}'='${value//\//\\/} filename

bash表达式${option//\//\\/}引用斜杠，它将所有/替换为\/。

注意:刚刚陷入了一个问题。在bash中，你可以引用"${option//\//\\/}"，但在busybox的sh中，这行不通，所以你应该避免使用引号，至少在非boure -shell中是这样。

所有这些组合在一个bash函数中:

# call option with parameters: $1=name $2=value $3=file
function option() {
    name=${1//\//\\/}
    value=${2//\//\\/}
    sed -i \
        -e '/^#\?\(\s*'"${name}"'\s*=\s*\).*/{s//\1'"${value}"'/;:a;n;ba;q}' \
        -e '$a'"${name}"'='"${value}" $3
}

解释:

/^\(option=\).*/: Match lines that start with option= and (.*) ignore everything after the =. The \(…\) encloses the part we will reuse as \1later. /^#?(\s*'"${option//////}"'\s*=\s*).*/: Ignore commented out code with # at the begin of line. \? means «optional». The comment will be removed, because it is outside of the copied part in \(…\). \s* means «any number of white spaces» (space, tabulator). White spaces are copied, since they are within \(…\), so you do not lose formatting. /^\(option=\).*/{…}: If matches a line /…/, then execute the next command. Command to execute is not a single command, but a block {…}. s//…/: Search and replace. Since the search term is empty //, it applies to the last match, which was /^\(option=\).*/. s//\1value/: Replace the last match with everything in (…), referenced by \1and the textvalue` :a;n;ba;q: Set label a, then read next line n, then branch b (or goto) back to label a, that means: read all lines up to the end of file, so after the first match, just fetch all following lines without further processing. Then q quit and therefore ignore everything else. $aoption=value: At the end of file $, append a the text option=value

关于sed和命令概述的更多信息请参阅我的博客:

https://marc.wackerlin.ch/computer/stream-editor-sed-overview-and-reference

保持简单就好:)

Grep + echo就足够了:

grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar

-q安静点 -x匹配整行 -F pattern是一个普通字符串 https://linux.die.net/man/1/grep

编辑: 合并了@cerin和@thijs-wouters的建议。

使用awk

awk 'FNR==NR && /configs.*projectname\.conf/{f=1;next}f==0;END{ if(!f) { print "your line"}} ' file file

下面是sed版本:

sed -e '\|include "/configs/projectname.conf"|h; ${x;s/incl//;{g;t};a\' -e 'include "/configs/projectname.conf"' -e '}' file

如果字符串在变量中:

string='include "/configs/projectname.conf"'
sed -e "\|$string|h; \${x;s|$string||;{g;t};a\\" -e "$string" -e "}" file

下面是一个单行sed，它内联完成这项工作。注意，当变量存在时，它会保留变量的位置及其在文件中的缩进。这对于上下文来说通常很重要，比如当周围有注释时，或者当变量位于缩进块中时。任何基于“先删除再追加”范式的解决方案在这方面都失败得很厉害。

   sed -i '/^[ \t]*option=/{h;s/=.*/=value/};${x;/^$/{s//option=value/;H};x}' test.conf

对于一个通用的变量/值对，你可以这样写:

   var=c
   val='12 34' # it handles spaces nicely btw
   sed -i '/^[ \t]*'"$var"'=/{h;s/=.*/='"$val"'/};${x;/^$/{s//c='"$val"'/;H};x}' test.conf

最后，如果还想保留内联注释，可以使用catch组。例如，如果test.conf包含以下内容:

a=123
# Here is "c":
  c=999 # with its own comment and indent
b=234
d=567

然后运行这个

var='c'
val='"yay"'
sed -i '/^[ \t]*'"$var"'=/{h;s/=[^#]*\(.*\)/='"$val"'\1/;s/'"$val"'#/'"$val"' #/};${x;/^$/{s//'"$var"'='"$val"'/;H};x}' test.conf

生产:

a=123
# Here is "c":
  c="yay" # with its own comment and indent
b=234
d=567

只使用sed，我建议使用以下解决方案:

sed -i \
    -e 's#^include "/configs/projectname.conf"#include "/configs/projectname.conf"#' \
    -e t \
    -e '$ainclude "/configs/projectname.conf"' lighttpd.conf

将include“/configs/projectname.conf”行替换为自身(此处使用#作为分隔符)

T如果替换成功，跳过其余命令

$a否则跳转到最后一行，并在其后添加include "/configs/projectname.conf "