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I frequently refer to man bash to recall use of "history expansion" parts(events/words/modifiers). I know that the man part I need is "HISTORY EXPANSION". So I type in HISTORY EXPANSION in forward search list '/'. Of course less jumps not straightforward to the "HISTORY EXPANSION" part, but instead shows all occurrences of this string in given man. Thus, I thought it would be great to type something like:

/^HISTORY EXPANSION

so I could jump to "start of line"HISTORY EXPANSION.

Neither /^HISTORY EXPANSION nor /\^HISTORY EXPANSION work

In less man I see that ...

/pattern
Search forward in the file for the N-th line containing the pattern. N defaults to 1. The pattern is a regular expression, as recognized by the regular expression library supplied by your system.

I see that other men were also looking into this, but with a different purpose: https://stackoverflow.com/questions/14698364/what-is-the-regular-expression-library-supplied-by-my-system

I followed the steps, but still cannot say for sure what regex version is used on my machine. Here is the shared lib dependencies output for less binary

$ ldd /usr/bin/less
linux-vdso.so.1 =>  (0x00007ffc229cb000)
libtinfo.so.5 => /lib/x86_64-linux-gnu/libtinfo.so.5 (0x00007f44968e9000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f4496524000)
/lib64/ld-linux-x86-64.so.2 (0x00007f4496b12000)

So, how to indicate start of line in less search, so I can easily jump to the parts of man I need?

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  • 1
    Typing /^HISTORY EX followed by return works for me in the manual of bash on a Linux system. I can't reproduce your issue.
    – Kusalananda
    Commented Jan 22, 2018 at 11:09
  • man is not really appropriate for a manual this big. I would recommand formats with support for index and/or table of content, like info with which you have a searchable index (i, then type history expansion with tab completion) Commented Jan 22, 2018 at 11:10
  • IOW, I can reproduce your issue if I run man as GROFF_SGR=1 MANPAGER='less -r' man bash. You'd want to make sure less is run with -R instead of -r (for it do understand those SGR escape sequences as opposed to pass them through), or use GROFF_NO_SGR to revert to the traditional way of doing bold/underline. Commented Jan 22, 2018 at 11:28
  • @Kusalananda set PAGER=more, and your search will fail. Commented Jan 22, 2018 at 11:29

2 Answers 2

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Having tried and experimented it appears that man actually indents lines with spaces. This is the reason I could find
/^HISTORY EXPANSION
and failed with
/^The history library(This is the first sentence in HISTORY EXPANSION section). Here is the correct pattern:
/^[[:space:]]{7}The history library...
As we can see man/less simply adds 7 "spaces"(ascii dec code 32) in front of each line that is not a section header (in bold, as I see other people speak). I cannot say for sure whether this is true with all Linux distros/man binaries, but with all I tested so far this is true. To sum up in order to find(from first search) description of '-atime' option in man find use
/^[[:space:]]{7}-atime

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When man's output passes through more, each bold character is in fact that character, followed by a backspace, followed by repeating that character and then to the next character. To find something in bold, search for /^H..I..S..T

You'll find it also in the article Stéphane pointed to.

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    But less understands those and its search facility will work on the rendered text. It's different though when roff uses SGR escape sequences for bold/underline and less is called with -r. Commented Jan 22, 2018 at 11:31

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