bash 什么是用于删除行的前 N 个字符的 unix 命令？
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What is a unix command for deleting the first N characters of a line?
提问by les2
For example, I might want to:
例如，我可能想要：
tail -f logfile | grep org.springframework | <command to remove first N characters>
I was thinking that trmight have the ability to do this but I'm not sure.
我在想这tr可能有能力做到这一点，但我不确定。
回答by iammichael
Use cut. Eg. to strip the first 4 characters of each line (i.e. start on the 5th char):
使用cut. 例如。去除每行的前 4 个字符（即从第 5 个字符开始）：
tail -f logfile | grep org.springframework | cut -c 5-
回答by LB40
sed 's/^.\{5\}//' logfile
and you replace 5 by the number you want...it should do the trick...
然后你用你想要的数字替换 5 ......它应该可以解决问题......
EDITif for each linesed 's/^.\{5\}//g' logfile
编辑if 对于每一行sed 's/^.\{5\}//g' logfile
回答by Ankur
You can use cut:
您可以使用cut：
cut -c N- file.txt > new_file.txt
-c:characters
-c:人物
file.txt:input file
file.txt:输入文件
new_file.txt:output file
new_file.txt:输出文件
N-:Characters from N to end to be cut and output to the new file.
N-:从 N 到 end 的字符被剪切并输出到新文件。
Can also have other args like: 'N' , 'N-M', '-M' meaning nth character, nth to mth character, first to mth character respectively.
也可以有其他参数，如： 'N' 、 'N-M'、 '-M' 分别表示第 n 个字符、第 n 个到第 m 个字符、第一个到第 m 个字符。
This will perform the operation to each line of the input file.
这将对输入文件的每一行执行操作。
回答by les2
tail -f logfile | grep org.springframework | cut -c 900-
would remove the first 900 characters
将删除前 900 个字符
cutuses 900- to show the 900th character to the end of the line
cut使用 900- 显示行尾的第 900 个字符
however when I pipe all of this through grep I don't get anything
但是，当我通过 grep 管道所有这些时，我什么也没得到
回答by John B
I think awkwould be the best tool for this as it can both filter and perform the necessary string manipulation functions on filtered lines:
我认为awk这将是最好的工具，因为它可以过滤并在过滤的行上执行必要的字符串操作功能：
tail -f logfile | awk '/org.springframework/ {print substr(tail -f logfile | awk '/org.springframework/ && sub(/^.{5}/,"",##代码##)'
, 6)}'
or
或者
##代码##回答by To Kra
Here is simple function, tested in bash. 1st param of function is string, 2nd param is number of characters to be stripped
这是简单的功能，在 bash 中测试。函数的第一个参数是字符串，第二个参数是要删除的字符数
function stringStripNCharsFromStart {
echo ${1:$2:${#1}}
}
function stringStripNCharsFromStart {
echo ${1:$2:${#1}}
}
Usage:
用法：
