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 "

 sed -i 's/^option.*/option=value/g' /etc/fdm_monitor.conf
 grep -q "option=value" /etc/fdm_monitor.conf || echo "option=value" >> /etc/fdm_monitor.conf

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。

下面是一个awk实现

/^option *=/ { 
  print "option=value"; # print this instead of the original line
  done=1;               # set a flag, that the line was found
  next                  # all done for this line
}
{print}                 # all other lines -> print them
END {                   # end of file
  if(done != 1)         # haven't found /option=/ -> add it at the end of output
    print "option=value"
}

使用

awk -f update.awk < /etc/fdm_monitor.conf > /etc/fdm_monitor.conf.tmp && \
   mv /etc/fdm_monitor.conf.tmp /etc/fdm_monitor.conf

or

awk -f update.awk < /etc/fdm_monitor.conf | sponge /etc/fdm_monitor.conf

编辑: 一句话:

awk '/^option *=/ {print "option=value";d=1;next}{print}END{if(d!=1)print "option=value"}' /etc/fdm_monitor.conf | sponge /etc/fdm_monitor.conf

我需要编辑一个文件限制写权限，所以需要sudo。从ghostdog74的答案工作，并使用一个临时文件:

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

使用awk

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