what does it mean '$=' in this script?
if [-f $1]
nblines=$(($(sed -n '$=' $1)))
I did research about '$=' about I found nothing.
Thank you
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total number of lines/buffer. it's like `wc -l` – Jetchisel Jul 14 '21 at 19:22
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1the `=` sets the line number in a given buffer/line. the `$` means the last line/buffer. and that is `sed` nothing to do with the shell. – Jetchisel Jul 14 '21 at 19:24
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2fwiw, google search on `sed "$="`: [this](https://www.grymoire.com/Unix/Sed.html), [this](https://www.gnu.org/software/sed/manual/sed.html) and [this](http://sed.sourceforge.net/grabbag/tutorials/do_it_with_sed.txt) – markp-fuso Jul 14 '21 at 19:32
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1what's the point of the `$(( ))` around it? Why not just `nblines=$(sed -n '$=' $1)`? – Paul Hodges Jul 14 '21 at 19:37
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I miss LMGTFY, lol... – Paul Hodges Jul 14 '21 at 19:38
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2@Paul, in case the file is empty, the arithmetic expansion will ensure the value `0` is saved in the variable, instead of an empty string. – glenn jackman Jul 14 '21 at 22:21
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2@houda, the first line is wrong: see https://github.com/koalaman/shellcheck/wiki/SC1035 – glenn jackman Jul 14 '21 at 22:24
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I do not understand how the duplicates explain what `$=` means in this particular script. – KamilCuk Aug 22 '21 at 13:13