diff

文本处理

用法

diff -u [old] [new]

显示两个文件之间改了什么；patch 和代码评审期待的是 -u 统一格式，而有差异时退出码是 1，会让开了 set -e 的脚本中断。

常用选项

选项	含义
-u	Unified output, the format patch and code review expect
-r	Compare two directory trees
-q	Only say whether the files differ
-w	Ignore all whitespace
-i	Ignore case
-N	Treat a missing file as empty, which patches need

示例

diff -u old.conf new.conf > fix.patch

Writes a patch file.

diff -rq dirA dirB

Lists which files differ between two trees.

diff <(sort a.txt) <(sort b.txt)

Compares two files ignoring line order (bash).

它们本来就是用管道串起来用的。串三条往往比让一条命令做完所有事更短。

怎么看

Q. diff 是做什么的？

显示两个文件之间改了什么；patch 和代码评审期待的是 -u 统一格式，而有差异时退出码是 1，会让开了 set -e 的脚本中断。

Q. 怎么写？

diff -u [old] [new] —— 方括号表示可以省略的部分。

Q. 值得记的选项有几个？

这里列了 6 个，完整列表在 man diff。这条命令属于文本处理。