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Full Discussion: find iname is being case sensitive
Top Forums UNIX for Advanced & Expert Users find iname is being case sensitive Post 302546560 by alister on Thursday 11th of August 2011 11:58:06 AM
Old 08-11-2011
Quote:
Originally Posted by COKEDUDE
Does shell expansion get handled differently in find with double quotes and single quotes than other programs? I know in grep shell expansion still happens with double quotes and not with with single quotes. I learned that from fpmurphy.
You need to understand that the shell's behavior is invariant with regard to what utilities you intend to invoke. The shell does not care one bit if you are trying to use find, or grep, or ls, or... The shell's job is basically to read a line of text, process that text according to its rules (expansions, substitutions, redirections, et al), and create a process running the desired utility with the requested arguments.

The invoked utility does not know or care if it was created by a command interpreting shell. It simply processes the arguments it was passed and gets to work.

Not knowing where the shell ends and a utility it invokes begins is a huge impediment to understanding what's going on. If this line is not clear to you, in my opinion, the most beneficial thing you could do in the very near future is to spend a few hours with the command parsing section of your shell man page, until you understand it thoroughly. It will serve you very, very well. Once you get it, you can look at the most complicated stuff and work your way through it.

You'll learn the order in which the shell performs substitutions and expansions. It'll also become trivial to understand the effects of quoting. In short, any text enclosed by single quotes (aka strong quotes) is taken literally. Nothing special happens. Double quotes (aka weak quotes) bypasses only those shell expansions, substitutions, and parsing steps that could increase the number of fields (this includes field splitting on IFS characters and filename expansion). So, no matter how the text within the double quotes is modified by processing, in the end you'll always have a single field (this is why double quoted command substitutions in a for loop list are utterly pointless).

Note: There is one exception to the double quote rule: "$@" expands to multiple fields, one per positional parameter (a hack workaround to allow dealing with a list of items when there was no list type).

Also, it may help to understand the basics of the system's execve(2) system call, which is responsible for loading a new executable image, which includes passing the command line arguments and the environment.

Regards,
Alister
 

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LEARN ABOUT SUSE

platform::shell

platform::shell(n)					       Tcl Bundled Packages						platform::shell(n)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4							platform::shell(n)
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