了解为什么 ‘less’ 比 ‘more’ 命令更快，以有效导航文件

教學

More是一個*nix命令行，用於在控制台中顯示文件的內容。more命令的基本用法是對文件運行命令，如下所示：

閱讀更多： 通過示例學習‘cat’和‘tac’命令之間的區別

學習Linux ‘more’命令

# more /var/log/auth.log
View Contents of auth.log File
Apr 12 11:50:01 tecmint CRON[6932]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 11:50:01 tecmint CRON[6932]: pam_unix(cron:session): session closed for user root
Apr 12 11:55:01 tecmint CRON[7159]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 11:55:01 tecmint CRON[7160]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 11:55:01 tecmint CRON[7160]: pam_unix(cron:session): session closed for user root
Apr 12 11:55:02 tecmint CRON[7159]: pam_unix(cron:session): session closed for user root
Apr 12 12:00:01 tecmint CRON[7290]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:00:01 tecmint CRON[7290]: pam_unix(cron:session): session closed for user root
Apr 12 12:05:01 tecmint CRON[7435]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:05:01 tecmint CRON[7436]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:05:01 tecmint CRON[7436]: pam_unix(cron:session): session closed for user root
Apr 12 12:05:02 tecmint CRON[7435]: pam_unix(cron:session): session closed for user root
Apr 12 12:09:01 tecmint CRON[7542]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:09:01 tecmint CRON[7542]: pam_unix(cron:session): session closed for user root
Apr 12 12:10:01 tecmint CRON[7577]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:10:01 tecmint CRON[7577]: pam_unix(cron:session): session closed for user root
Apr 12 12:15:01 tecmint CRON[7699]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:15:01 tecmint CRON[7700]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 12:15:01 tecmint CRON[7700]: pam_unix(cron:session): session closed for user root
Apr 12 12:15:01 tecmint CRON[7699]: pam_unix(cron:session): session closed for user root
....

另一種使用more命令的方法是與其他命令一起使用（管道），例如cat命令，如下例所示：

# cat /var/log/auth.log | more
View and Navigate Contents of File

要逐行瀏覽文件，請按Enter鍵，或按Spacebar鍵以每次瀏覽一頁，該頁是您當前終端屏幕的大小。要退出命令，只需按q鍵。

A useful option of more command is the -number switch which allows you to set the number of line a page should contain. As an example display the auth.log file as a page of 10 lines:

# more -10 /var/log/auth.log
Show Only First 10 Lines of File

此外，您還可以使用+號碼選項顯示從特定行號開始的頁面，如下所示：

# more +14 /var/log/auth.log
Show Only First 14 Lines of auth.log File
Apr 12 12:09:01 tecmint CRON[7542]: pam_unix(cron:session): session closed for user root
Apr 12 12:10:01 tecmint CRON[7577]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:10:01 tecmint CRON[7577]: pam_unix(cron:session): session closed for user root
Apr 12 12:15:01 tecmint CRON[7699]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:15:01 tecmint CRON[7700]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:15:01 tecmint CRON[7700]: pam_unix(cron:session): session closed for user root
Apr 12 12:15:01 tecmint CRON[7699]: pam_unix(cron:session): session closed for user root
Apr 12 12:16:01 tecmint mate-screensaver-dialog: gkr-pam: unlocked login keyring
Apr 12 12:17:01 tecmint CRON[7793]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:17:01 tecmint CRON[7793]: pam_unix(cron:session): session closed for user root
Apr 12 12:20:01 tecmint CRON[7905]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:20:01 tecmint CRON[7905]: pam_unix(cron:session): session closed for user root
Apr 12 12:25:01 tecmint CRON[8107]: pam_unix(cron:session): session opened for user root by (
uid=0)
Apr 12 12:25:01 tecmint CRON[8108]: pam_unix(cron:session): session opened for user root by (

學習Linux‘less’命令

與more類似，less命令允許您查看文件的內容並通過文件進行導航。more和less之間的主要區別在於less命令更快，因為它不會一次加載整個文件，並且允許使用頁面上/下鍵進行文件導航。

`less` 命令可用作针对文件的独立命令，也可与多种 Linux 命令一起使用管道，以缩小屏幕输出范围，使您能够浏览结果。

# less /var/log/auth.log
# ls /etc | less

您可以通过按 Enter 键逐行导航文件。页面导航可使用 spacebar 键处理。页面大小由当前终端屏幕大小表示。要退出命令，请输入 q 键，与 more 命令相同。

A useful feature of less command is the use of /word-to-seach option. For instance you can search and match all sshd messages from a log file by interactively specifying the /sshd string.

View File Content Using less Command

要显示从特定行号开始的文件，请使用以下语法：

# less +5 /var/log/auth.log

如果需要使用 `less` 命令跟踪每一行的编号，请使用 -N 选项。

# less -N /var/log/daemon.log
Show Number for Every Line in File
      1 Apr 12 11:50:01 tecmint CRON[6932]: pam_unix(cron:session): session opened for user root by (uid=0)
      2 Apr 12 11:50:01 tecmint CRON[6932]: pam_unix(cron:session): session closed for user root
      3 Apr 12 11:55:01 tecmint CRON[7159]: pam_unix(cron:session): session opened for user root by (uid=0)
      4 Apr 12 11:55:01 tecmint CRON[7160]: pam_unix(cron:session): session opened for user root by (uid=0)
      5 Apr 12 11:55:01 tecmint CRON[7160]: pam_unix(cron:session): session closed for user root
      6 Apr 12 11:55:02 tecmint CRON[7159]: pam_unix(cron:session): session closed for user root
      7 Apr 12 12:00:01 tecmint CRON[7290]: pam_unix(cron:session): session opened for user root by (uid=0)
      8 Apr 12 12:00:01 tecmint CRON[7290]: pam_unix(cron:session): session closed for user root
      9 Apr 12 12:05:01 tecmint CRON[7435]: pam_unix(cron:session): session opened for user root by (uid=0)
     10 Apr 12 12:05:01 tecmint CRON[7436]: pam_unix(cron:session): session opened for user root by (uid=0)
     11 Apr 12 12:05:01 tecmint CRON[7436]: pam_unix(cron:session): session closed for user root

默认情况下，退出 `less` 命令的唯一方法是按下 q 键。要更改此行为，并在到达文件末尾时自动退出文件，请使用 -e 或 -E 选项：

# less -e /var/log/auth.log
# less -E /var/log/auth.log

要在首次出现模式时打开文件，请使用以下语法：

# less +/sshd /var/log/auth.log
Show Given Matching String in File
Apr 12 16:19:39 tecmint sshd[16666]: Accepted password for tecmint from 192.168.0.15 port 41634 ssh2
Apr 12 16:19:39 tecmint sshd[16666]: pam_unix(sshd:session): session opened for user tecmint by (uid=0)
Apr 12 16:19:39 tecmint systemd-logind[954]: New session 1 of user tecmint.
Apr 12 16:19:48 tecmint sshd[16728]: Received disconnect from 192.168.0.15: 11: disconnected by user
Apr 12 16:19:48 tecmint sshd[16666]: pam_unix(sshd:session): session closed for user tecmint
Apr 12 16:20:01 tecmint CRON[16799]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 16:20:02 tecmint CRON[16799]: pam_unix(cron:session): session closed for user root
Apr 12 16:25:01 tecmint CRON[17026]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 12 16:25:01 tecmint CRON[17025]: pam_unix(cron:session): session opened for user root by (uid=0)

上述命令告诉 `less` 在第一次匹配 `sshd` 字符串时打开 `auth.log` 文件。

要在 `less` 命令中自动追加文件内容，请使用 `Shift+f` 键组合或以以下语法运行 less。

# less +F /var/log/syslog

这使 `less` 在交互模式下运行（实时），并在等待写入文件的新数据时即时显示新内容。此行为类似于 `tail -f` 命令。

結合一個模式，您可以在匹配關鍵字的同時使用 Shift+f 鍵進行交互式觀看日誌文件。要退出實時模式，只需按下 Ctrl+c 鍵。

# less +/CRON /var/log/syslog

無論您決定使用 more 還是 less，這是一個個人選擇，請記住 less 是帶有 more 功能的更少。

閱讀更多： 使用 head、tail 和 cat 命令有效管理文件

Source:
https://www.tecmint.com/linux-more-command-and-less-command-examples/