① 定义grep是行级设备，它分析一行信息，若当中有我们所需要的信息，就将整行返回
② 作用进行字符串数据的对比，将符合用户需求的字符串打印出来
③ 格式grep [-acinv] [–color=auto] ‘查找字符串’ filename参数：-a：将二进制文件一text文件的方式查找数据-c：计算找到‘查找字符串’的次数-i：对大小写透明-n：输出行号-v：显示没有‘查找字符串’内容的那一行-A:后面可加数字，为after的意思，除了列出该行外，后续的n行也列出来-B:后面可加数字，，为before的意思，除了列出该行外，前面的n行也列出来–color=auto：关键字上色
④ 例子eg01：找出有检查点事件发生的标志
[Oracle@localhost bdump]$ grep -in –color=auto ‘checkpoint’ alert_orcl.log64: checkpoint is 44607466: checkpoint is 44607469: checkpoint is 44607472: checkpoint is 446074383: checkpoint is 4602001845:Checkpoint not complete2112: checkpoint is 6062172114: checkpoint is 6062172116: checkpoint is 6062172118: checkpoint is 6062172120: checkpoint is 606217
eg02：从内核中找出网卡相关信息
[oracle@localhost bdump]$ dmesg | grep -n -A3 -B2 –color=auto ‘eth’599-iscsi: registered transport (iser)600-iscsi: registered transport (be2iscsi)601:eth0: no IPv6 routers present602-Bluetooth: Core ver 2.10603-NET: Registered protocol family 31604-Bluetooth: HCI device and connection manager initialized–615-ip_conntrack version 2.4 (8192 buckets, 65536 max) – 228 bytes per conntrack616-ip6_tables: (C) 2000-2006 Netfilter Core Team617:peth0: Promiscuous mode enabled.618:device peth0 entered promiscuous mode619:xenbr0: port 1(peth0) entering forwarding state620-device vif0.0 entered promiscuous mode621-New device vif0.0 does not support netpoll622-Disabling netpoll for xenbr0–625-hdc: drive_cmd: error=0x04 { AbortedCommand }626-ide: failed opcode was: 0xec627:eth0: no IPv6 routers present628:xenbr0: port 1(peth0) entering disabled state629:xenbr0: port 1(peth0) entering forwarding state
临行之前，面对太多的疑问和不解：为何是一个人？
