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我所知道和经常使用的

tag-icon • tag-icon command-line less
我所知道和经常使用的

我所知道和经常使用的

less我喜欢如何使用+命令行中的 - 参数添加命令。我喜欢这样进行即时搜索：

$ less +/DHCP /var/log/syslog
# result: syslog at the point of the first occurrence of DHCP

但我也喜欢将其设置为遵循这样的输出：

$ less +F /var/log/syslog
# result: a syslog that follows the file, very much like tail -f would.

我想用什么

但每隔一段时间我就会两者都想要。但我不知道该怎么做。

$ less +F +/DHCP /var/log/syslog
# result: "Pattern not found" - it will actually bunch up both things to one string.

谁能告诉我如何自动过滤而不必在开始时按下，谁能给我加分？

$ less +\&DHCP /var/log/syslog
# result: "please press enter" after which the filtering search _is_
# running correctly. I would love to get rid of that extra <enter>

edit2：有趣的是，我可以将这些结合起来：

$ less +?DHCP +G /var/log/syslog
# result: jumps to the end and reverse-searches for DHCP
# But I have to press enter (which I'd like to avoid)

但我不能这样做：

$ less +G +?DHCP /var/log/syslog
# this is being bunched up to ?DHCPG and subsequently not found.

那么，顺序似乎很重要，所有字符串都被解释为一个字符串？

版本信息

编辑这是我的系统上安装的 less 版本，但如果需要的话我愿意安装另一个版本！

$ less --version
less 458 (GNU regular expressions)
Copyright (C) 1984-2012 Mark Nudelman
[...]

答案1

根据您后来的评论，我认为我不理解您问题的第一部分。对我来说，使用less +F +/pattern logfile有效并继续突出显示pattern更新文件中出现的新实例。

至于问题的奖励部分，您可以尝试以下命令之一：

less +\&DHCP$'\n' /var/log/syslog

或者

less +\&DHCP^M /var/log/syslog

在第二个命令中，通过按then^M生成。当 less 启动时，按 Enter 会更容易，除非你想编写脚本或其他东西。Ctrl-VEnter

答案2

在巨大的过度复杂性方面：通过包装器使用可更改的搜索词自动尾随expect！

#!/usr/bin/env expect
#
# Sticky search wrapper for less; tails the given file, though with
# input of
#   /asdf
# or whatever will search for that new term then re-tail the file.
# Probably needs `less` with (the default) hilight mode enabled.

if {[llength $argv] == 0} {
  puts stderr {Usage: $argv0 [searchterm] file}
  exit 64
} elseif {[llength $argv] == 1} {
  set fname [lindex $argv 0]
  set search ""
} else {
  set fname [lindex $argv 1]
  set search [lindex $argv 0]
}

# FIXME soas to nix any default options (like turning off hilight) and
# on account of LESSOPEN and LESSCLOSE being security risks due to the
# defaults certain vendors set.
foreach ev [list LESS LESSOPEN LESSCLOSE] {
  if {[info exists env($ev)]} {
    unset env($ev)
  }
}

match_max 999
set timeout -1

spawn -noecho less $fname
expect {
  # TODO need better way to detect that less didn't fly...
  -ex "No such file or directory" { exit }
  -re "." { }
  default { exit }
}

if {$search ne ""} {
  send -- "/$search\r"
}
send -raw "F"
interact {
  -echo -re "/(.*)\[\n\r]" {
#   send_user "DBG search $interact_out(1,string)"
    send -raw "\003\r/"
    send -- $interact_out(1,string)
    send -raw "\rF"
  }
}

答案3

据我了解，您想要读取该/var/log/syslog文件，并查看带有“DHCP”的所有条目，并不断查看出现的新条目。如果这是正确的，则可以通过 来实现tail -f /var/log/syslog | grep DHCP。如果我对您的请求的解释不正确，我哪里出错了？

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