[Discussion] POSIX, the Love of Backticks and All That Jazz Post: 302990516

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Top Forums UNIX for Advanced & Expert Users [Discussion] POSIX, the Love of Backticks and All That Jazz Post 302990516 by bakunin on Friday 27th of January 2017 12:17:49 PM

01-27-2017

Registered User

Quote:

Originally Posted by Peasant

If i'm not mistaken backquotes are still the lowest common denominator for command substitution if you wish your scripts to work anywhere without touching

This is an interesting argument.

IMHO the "gold standard" of portability is POSIX: if something is POSIX, then it can (and should) be used, if it not, it should be handled with extreme care (and eventually not be used in absence of compelling reasons why it should).

The construct $(..) now is in fact the POSIX-standard for doing this (subshells) and backticks `...` are deprecated. This is why i use the former rather than the latter and recommend this practice to others.

For the same reason i write i.e. tail -n 5 instead of tail -5. The former is POSIX, the latter deprecated. It may be that there is some (really old) system out there which would not recognise the new syntax but only the old one. This risk i am willing to take because, on the the other hand, there might be a really new system which has cut off old behaviorisms and only understands the current syntax.

I hope this helps.

bakunin

Moderator's Comments:

PS: this discussion is very interesting but we are getting off topic in relation the threads original theme. If anyone wants to continue this i suggest to split this thread and carry on in a new one. Just post here if you want to contribute and i will take care of the splitting if there are any takers.

bakunin

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inotail

INOTAIL(1)						       Inotify enhanced tail							INOTAIL(1)

NAME

       inotail - A fast and lightweight version of tail using inotify

SYNOPSIS

       inotail [OPTION]... [FILE]...

DESCRIPTION

       inotail	is a replacement for the 'tail' program found in the base installation of every Linux/UNIX system. It makes use of the inotify in-
       frastructure in recent versions of the Linux kernel to speed up tailing files in the follow mode (the '-f' option). Standard tail polls the
       file every second by default while inotail listens to special events sent by the kernel through the inotify API to determine whether a file
       needs to be reread. Note: inotail will not work on systems running a kernel without inotify. To enable inotify, please set CONFIG_INOTIFY=y
       in your Linux kernel configuration and recompile it.

       Currently inotail is not fully compatible to neither POSIX or GNU tail but might be in the future.

OPTIONS

       -c N, --bytes=N
	      output the last N bytes. If the first character of N is a '+', begin printing with the Nth character from the start of each file.

       -f, --follow
	      keep the file(s) open and print appended data as the file grows

       -n N, --lines=N
	      output  the last N lines (default: 10) If the first character of N is a '+', begin printing with the Nth line from the start of each
	      file.

       -v, --verbose
	      print headers with file names

       -h, --help
	      show help and exit

       -V, --version
	      show inotail version and exit

AUTHOR

       Written by Tobias Klauser <tklauser@distanz.ch>

SEE ALSO

       tail(1), inotify(7)

								    2006-08-13								INOTAIL(1)