Shell编程中的常用命令diff和patch
diff和patch命令
diff通常比较文件的内容(产生补丁文件)，patch常用来打补丁
<表示第一个文件中的内容
>表示第二个文件中的内容
diff -u
diff -r #比较目录
diff通常比较目录的时候 比较的结果是目录中文件的不同，不能比较文件内容的不同
(有没有相同名字的文件)
a表示添加 ----add
c表示更改 ----change
d表示删除 ----delete
Diff file1 file2 #以第二个文件为基准，看第一个文件跟第二个文件的区别(第一个如何能变成第二个文件)
[root@localhost diff_patch]# cat file1
123
haha
[root@localhost diff_patch]# cat file2
123
nihao
[root@localhost diff_patch]# diff file1 file2
2c2
#第一个2是第一个文件的第二行 c:动作更改 第二个2:第二个问文件的第二行
#表示第一个文件中的第二行改变了后可以变为第二行
< haha #第一个文件的第二行的内容
---
> nihao
#第二个文件的第二行的内容(第一个文件的第二行内容将要变成的东西)
[root@localhost diff_patch]# diff file2 file1 file2如何才能变成file1
2c2
< nihao
---
> haha
[root@localhost diff_patch]# cat file1
123
[root@localhost diff_patch]# cat file2
123
nihao
[root@localhost diff_patch]# diff file1 file2
1a2 #第一个文件的第一行
> nihao #将第二文件的第二行内容加到第一个文件第一行上
[root@localhost diff_patch]# diff file2 file1
2d1 #第一个文件的第二删除第一个文件的内容nihao，就得到第二个文件了
< nihao
diff -u：-u表示产生补丁， 以第二个文件为标准(最终变成的文件)
diff -u file1 file2
[root@localhost diff_patch]# diff -u file1 file2
--- file1 2020-02-15 10:55:10.502000000 +0800
+++ file2 2020-02-15 10:44:02.246000000 +0800
@@ -1 +1,2 @@
123
+nihao
diff -u file1 file2 > file2.patch
[root@localhost diff_patch]# diff -u file1 file2 > file2.patch
[root@localhost diff_patch]# cat file2.patch
--- file1 2020-02-15 10:55:10.502000000 +0800
+++ file2 2020-02-15 10:44:02.246000000 +0800
@@ -1 +1,2 @@
123
+nihao
[root@localhost diff_patch]# patch file2 file2.patch
bash: patch: command not found...
#发现没有装patch命令
[root@localhost yum.repos.d]# yum clean all
[root@localhost yum.repos.d]# yum repolist
[root@localhost yum.repos.d]# yum whatprovides */patch
……
Filename : /usr/src/kernels/3.10.0-514.el7.x86_64/include/config/snd/hda/patch
patch-2.7.1-8.el7.x86_64 : Utility for modifying/upgrading files
Repo : test
Matched from:
Filename : /usr/bin/patch
[root@localhost yum.repos.d]# yum install -y patch-2.7.1-8.el7.x86_64
[root@localhost diff_patch]# diff -u file1 file2 > file1.patch
[root@localhost diff_patch]# ls
file1 file1.patch file2 file2.patch hui.dudu
[root@localhost diff_patch]# rm -fr file2.patch
[root@localhost diff_patch]# ls
file1 file1.patch file2 hui.dudu
patch file1 file1.patc
[root@localhost diff_patch]# patch file1 file1.patch #不保留原文件(内容)
#这样打补丁原文件就没有了(不推荐)
#给file1打补丁，来和file2一样
patching file file1
[root@localhost diff_patch]# diff file1 file2
[root@localhost diff_patch]# cat file1
123
nihao
[root@localhost diff_patch]# cat file2
123
nihao
[root@localhost diff_patch]#
[root@localhost diff_patch]# cat file1
123
nihao
[root@localhost diff_patch]# cat file3
123
Haha
[root@localhost diff_patch]# diff -u file3 file1
--- file3 2020-02-15 11:50:58.543000000 +0800
+++ file1 2020-02-15 11:44:35.921000000 +0800
@@ -1,2 +1,2 @@
123
-haha
+nihao
产生file3的补丁
[root@localhost diff_patch]# diff -u file3 file1 > file3.patch
[root@localhost diff_patch]# ls
file1 file1.patch file2 file3 file3.patch hui.dudu
patch -b file3 file3.patch
(保留原文件内容，打完补丁后，生成.orig文件(内容与原文件相同))
[root@localhost diff_patch]# patch -b file3 file3.patch
patching file file3
[root@localhost diff_patch]# ls
file1 file1.patch file2 file3 file3.orig file3.patch hui.dudu
[root@localhost diff_patch]# cat file3.orig
123
haha
diff -r比较目录
[root@localhost diff_patch]# diff /etc/ /tmp/
Only in /etc/: abrt
Only in /etc/: adjtime
Only in /etc/: aliases
Only in /etc/: aliases.db
作者：huige永生
