[英]Find a line in a file and add something to the end of the line in bash
How can I identify a line start with a special pattern and add something to the end of the line? 如何识别具有特殊模式的行开头并在行尾添加一些内容?
if the pattern that should be added is not already appended 如果尚未附加应添加的模式
Let's say I'd like to find a specific line in the host file either by the pattern at the beginning may be an ip-address or by the comment that is above the line 假设我想通过开头的模式在主机文件中找到一个特定的行,可能是ip-address,也可能是行上方的注释
An example may be: 一个例子可能是:
#This is your hosts file
127.0.0.1 localhost linux
#This is added automatically
192.168.1.2 domain1. com
#this is added automatically to
192.168.1.2 sub.domain1.com www.domain1.com
How do I tell bash when you find the IP I tell you. 当你找到我告诉你的IP时,我如何告诉bash。 go ro the lines end and add something
去结束并添加一些东西
or the other case 或其他情况
When bash finds the comment #This is added automatically
当bash发现评论时
#This is added automatically
go down by 2 and than go to the end of the line and add something 往下走2,然后到最后一行添加一些东西
You see I'm a beginner and don't have any Idea what to use here and how. 你看我是初学者,并且没有任何想法在这里使用什么以及如何使用。 Is dis done by sed?
是由sed解决? or could this be done with grep?
或者这可以用grep完成吗? do I have to learn AWK for that stuff?
我必须学习AWK吗?
This will add some text to the end of the line with a pattern "127.0.0.1". 这将在行尾添加一些文本,格式为“127.0.0.1”。
grep -F "127.0.0.1" file | sed -ie 's/$/& ADDing SOME MORE TEXT AT THE END/g'
Following will add to the line in the file that begins with 127.0.0.1
via sed : 以下将通过sed添加到以
127.0.0.1
开头的文件中的行:
sed -ie 's/^127.0.0.1.*$/& ADDing MORE TEXT TO THE END/g' file
TO do the same, you can also use awk
: 要做同样的事情,你也可以使用
awk
:
awk '/^127.0.0.1/{print $0,"ADD MORE TEXT"}' file > newfile && mv newfile file
If you want to call the IP address through a variable then syntax might be a bit different : 如果要通过变量调用IP地址,则语法可能略有不同:
var="127.0.0.1"
grep -F "$var" file | sed -ie 's/$/& ADD MORE TEXT/g'
sed -ie "s/^$var.*$/& ADD MORE TEXT/g" file
awk '/^'$var'/{print $0,"ADD MORE TEXT"}' file > newfile && mv newfile file
Given the following: 鉴于以下内容:
Textfile: 文本文件:
[root@yourserver ~]# cat text.log
#This is your hosts file
127.0.0.1 localhost linux
[root@yourserver ~]#
bash script: bash脚本:
[root@yourserver ~]# cat so.sh
#!/bin/bash
_IP_TO_FIND="$1"
# sysadmin 101 - the sed command below will backup the file just in case you need to revert
_BEST_PATH_LINE_NUMBER=$(grep -n "${_IP_TO_FIND}" text.log | head -1 | cut -d: -f1)
_LINE_TO_EDIT=$(($_BEST_PATH_LINE_NUMBER+2))
_TOTAL_LINES=$( wc -l text.log)
if [[ $_LINE_TO_EDIT -gte $_TOTAL_LINES ]]; then
# if the line we want to add this to is greater than the size of the file, append it
sed -i .bak "a\${_LINE_TO_EDIT}i#This is added automatically\n\n192.168.1.2 domain1. com" text.log
else
# else insert it directly
sed -i .bak "${_LINE_TO_EDIT}i\#This is added automatically\n\n192.168.1.2 domain1. com" text.log
fi
Usage: 用法:
bash ./so.sh 127.0.0.1
Simply enter in the ip address you're trying to find and this script matches on the first occurrence of it. 只需输入您要查找的IP地址,此脚本在第一次出现时就匹配。
Hope this helps! 希望这可以帮助!
This inline sed should work: 这个内联sed应该工作:
sed -i.bak 's/^192\.168\.1\.2.*$/& ADDED/' hosts
192.168.1.2
192.168.1.2
开头的行 ADDED
at the end of those lines ADDED
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