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Top Forums UNIX for Advanced & Expert Users [Discussion] POSIX, the Love of Backticks and All That Jazz Post 302990658 by Peasant on Monday 30th of January 2017 10:49:20 AM
Old 01-30-2017
Lets not get deep into subshells.

I'm sure you experts don't have too many nested subshells in your code Smilie
In my opinion, it lowers the control you have in your program.

So if you have small, efficient script with no nested subshells, are backquotes still the lowest denominator e.g will it run without magic cookie on any unix OS ever produced ?

Example would be a simple mv script using basename command in subshell.
 

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fileutil::magic::cfront(n)					  file utilities					fileutil::magic::cfront(n)

__________________________________________________________________________________________________________________________________________________

NAME
fileutil::magic::cfront - Generator core for compiler of magic(5) files SYNOPSIS
package require Tcl 8.4 package require fileutil::magic::cfront ?1.0? package require fileutil::magic::cgen ?1.0? package require fileutil::magic::rt ?1.0? package require struct::list package require fileutil ::fileutil::magic::cfront::compile path... ::fileutil::magic::cfront::procdef procname path... ::fileutil::magic::cfront::install path... _________________________________________________________________ DESCRIPTION
This package provides the frontend of a compiler of magic(5) files into recognizers based on the fileutil::magic::rt recognizer runtime package. For the generator backed used by this compiler see the package fileutil::magic::cgen. COMMANDS
::fileutil::magic::cfront::compile path... This command takes the paths of one or more files and directories and compiles all the files, and the files in all the directories into a single recognizer for all the file types specified in these files. All the files have to be in the format specified by magic(5). The result of the command is a Tcl script containing the generated recognizer. ::fileutil::magic::cfront::procdef procname path... This command behaves like ::fileutil::magic::cfront::compile with regard to the specified path arguments, then wraps the resulting recognizer script into a procedure named procname, puts code setting up the namespace of procname in front, and returns the result- ing script. ::fileutil::magic::cfront::install path... This command uses ::fileutil::magic::cfront::procdef to compile each of the paths into a recognizer procedure and installs the result in the current interpreter. The name of each new procedure is derived from the name of the file/directory used in its creation, with file/directory "FOO" caus- ing the creation of procedure ::fileutil::magic::/FOO::run. BUGS, IDEAS, FEEDBACK This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category fileutil :: magic of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for either package and/or documentation. SEE ALSO
file(1), fileutil, magic(5) KEYWORDS
file recognition, file type, file utilities, mime, type CATEGORY
Programming tools fumagic 1.0 fileutil::magic::cfront(n)
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