Linux command-line reader (like "less") that can start in line x and return the current line

Question

[Context] I'm developing a little app, as a hobby to learn ncurses, that catalogs and lists and searches within a set of documents (for now, they are the HOWTOs from LDP).

The most tricky part of the app is, I believe, the file reader (show the contents of a file nicely). To really be able to provide a good enough user experience, given that the HOWTOs are somewhat long, it would be a valuable feature if I can "save" the line where the user stopped reading, and start on that same line the next time the user opens up that same HOWTO [/context]

So to the real question: is there a command-line reader that can not only get a line X as a parameter and position the cursor at that line, but also return the line that was last shown? Or, given that I'll be doing the call from a C app, maybe a different solution that's not an external app: I'm open to suggestions

Might be useful: http://superuser.com/questions/111016/vim-open-file-at-location-that-was-last-viewed or rereading your question maybe not :) — cowls, Jan 08 '13 at 13:25

score 1 · Answer 1 · edited May 23 '17 at 12:18

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but also return the line that was last shown

There is no portable solution to this. See Are there any standard exit status codes in Linux?. I.e.:

How would that program signal an error?
How would it signal success?
How would it signal line numbers larger than 255?

edited May 23 '17 at 12:18

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answered Jan 08 '13 at 13:22

Sebastian Mach

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Thanks, that's what I was afraid of... So I'll pretty much have to try a different approach to this – beder Jan 08 '13 at 13:24
@beder: I once tried to return arbitrary error codes, until I stumbled over the 255-maximum – Sebastian Mach Jan 08 '13 at 13:25
What about returning 0-254 as the percentage (how far down in the file the user looked), 255 as an error? – choroba Jan 08 '13 at 13:35
@choroba: You mean mapping 0-100% to the 0-254 range or plain just consider the file 254% read? – r_ahlskog Jan 08 '13 at 15:19
@choroba: But that would still mean the program is not able to indicate success and failure, therefore it would be against unix conventions. – Sebastian Mach Jan 08 '13 at 21:29

Linux command-line reader (like "less") that can start in line x and return the current line

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