A practical method to delete data at the end of a file in Linux

Title: Practical method to delete file tail data in Linux

In Linux systems, we often encounter situations where we need to delete file tail data, especially when the file contains When there is some invalid or unwanted data. This article will introduce several practical methods to delete file tail data, and provide specific code examples to help readers quickly implement them.

Method 1: Use the truncate command

Truncate is a command used to truncate the file size, which can truncate the file to a specific length. Data at the end of the file can be removed by specifying the length of the file to be truncated. The following is a sample code:

# 截断文件到指定长度
truncate -s -[字节数] [文件名]

Method 2: Use the dd command

The dd command is a very powerful tool in Linux and can be used to copy files, convert formats, and intercept files. The function of deleting data at the end of a file can be achieved through the dd command. The following is a sample code:

# 获取文件大小
filesize=$(stat -c "%s" [文件名])

# 计算删除的字节数
delete_bytes=[要删除的字节数]
total_bytes=$(($filesize - $delete_bytes))

# 使用dd删除文件尾部数据
dd if=[文件名] of=[新文件名] bs=1 count=$total_bytes

Method 3: Use the sed command

sed is a stream editor that can be used to replace, delete, and other operations on text. By combining the sed command with regular expressions, you can delete data at the end of the file. The following is a sample code:

# 删除文件尾部数据
sed -i '$d' [文件名]

Method 4: Use the awk command

awk is a powerful text processing tool that can be used to extract and process text content. The function of deleting the data at the end of the file can be achieved through the awk command. The following is a sample code:

# 获取文件总行数
line_count=$(wc -l < [文件名])

# 删除最后一行
head -n $(($line_count - 1)) [文件名] > [新文件名]

In summary, this article introduces four practical methods to delete file tail data in Linux systems, including using the truncate, dd, sed and awk commands. Readers can choose the appropriate method according to their own needs and practice it through the provided code examples. I hope the above content can help readers solve practical problems and improve work efficiency.

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