How to search a log file in Linux and escape special characters like square brackets (i.e. [ and ])

Can someone point me in the right direction on this?

I less the log file as per below:

less system001A.LOG

Once I am in the log, I then press < (i.e. the smaller-than sign), and then I press forward-slash (i.e./) and type what I would like to search for:

/ERROR [section_NAME]

The problem is how to escape these brackets while I search? Because when I run this, it says no pattern/match is found, yet this in fact exists on the log.

  • 5
    you need to escape the special characters by a backslash character. Like: /ERROR \[section_NAME\]
    – MelBurslan
    Apr 6, 2016 at 13:36
  • Have you tried to use /ERROR \[section_NAME\] Apr 6, 2016 at 13:36
  • No, that did not work. I tried that now.
    – NinjaLoop
    Apr 6, 2016 at 13:59
  • If the logfile has coloured text in it, you will have issues matching any of that.
    – Kusalananda
    Apr 17, 2018 at 17:21

2 Answers 2


The manual does mention you can switch off regular expression search for the whole search string by pressing ^R (CTRL+R) after you press /.

  • 2
    @ninjaloop Accept this headache-preventing answer!
    – Walf
    Aug 16, 2019 at 3:25

If you have GNU regex on your system (re_compile_pattern is found in C lib), then the escape character is the usual backslash (\). However, there are many different regex engines that less may be using, depends on how it was compiled: https://github.com/gwsw/less/blob/master/pattern.c#L25

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