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Full Discussion: How to add to the search path - bin?
Top Forums UNIX for Dummies Questions & Answers How to add to the search path - bin? Post 302901789 by bakunin on Thursday 15th of May 2014 03:42:16 PM
Old 05-15-2014
You haven't said which OS you are on, but i suppose it is some kind of Linux.

Notice, that there are two files: /etc/profile and/or /etc/bash.bashrc. These are systemwide settings and changing these will alter your system, so stay away from them as long as you are not sure what you do and how you do it.

Then there is "/your/home/.profile" and "/your/home/.bashrc". These files are only executed by you and you can - more or less - do whatever you want with them. The worst you might do is make login or execution of the shell for yourself impossible - log on as root, remove the offending files or replace them with some backup copy and you are again ready to go. You might want to create a separate "test user" for that purpose and experiment with the startup files for this account. Once you are satisfied you copy the files from there to your own home and use them.

Now to your initial question: "$PATH" is a list of directories, separated by colons (":") which are searched for executable files if no complete path is entered. A common PATH variable might look similar to this:

Code:
# echo $PATH
/bin:/usr/bin:/usr/sbin:/usr/local/bin

If you now enter "command" at the command line these directories are searched in the order they appear in this variable for a file which is executable and named "command": first "/bin/command", then "/usr/bin/command", etc..

Once such a file is found, it is executed. By changing the order within "$PATH" you can influence which executable (if there are several named identically) is executed. If you put "/your/home/bin" in front of your PATH by executing

Code:
PATH=/your/home/bin:$PATH

an executable named i.e. "/your/home/bin/cp" would "override" (take precedence over) the system command "cp", usually located in "/usr/bin/cp".

This is sometimes a wanted effect, sometimes not. You decide what you want here. You just need to know that writing "$PATH" is like typing the complete current value of the PATH variable, therefore, taking the above mentioned value as example:

Code:
# echo $PATH
/bin:/usr/bin:/usr/sbin:/usr/local/bin
# PATH=$PATH:/some/new/dir
# echo $PATH
/bin:/usr/bin:/usr/sbin:/usr/local/bin:/some/new/dir
# PATH=/other/dir:$PATH
# echo $PATH
/other/dir:/bin:/usr/bin:/usr/sbin:/usr/local/bin:/some/new/dir

etc..

I hope this helps.

bakunin
 

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LEARN ABOUT SUNOS

getusershell

getusershell(3C)					   Standard C Library Functions 					  getusershell(3C)

NAME

       getusershell, setusershell, endusershell - get legal user shells

SYNOPSIS

       #include <unistd.h>

       char *getusershell(void);

       void setusershell(void);

       void endusershell(void);

DESCRIPTION

       The  getusershell()  function  returns  a  pointer  to  a  legal  user  shell  as defined by the system manager in the file /etc/shells. If
       /etc/shells does not exist, the following locations of the standard system shells are used in its place:

       /bin/bash		  /bin/csh
       /bin/jsh 		  /bin/ksh
       /bin/pfcsh		  /bin/pfksh
       /bin/pfsh		  /bin/sh
       /bin/tcsh		  /bin/zsh
       /sbin/jsh		  /sbin/pfsh
       /sbin/sh 		  /usr/bin/bash
       /usr/bin/csh		  /usr/bin/jsh
       /usr/bin/ksh		  /usr/bin/pfcsh
       /usr/bin/pfksh		  /usr/bin/pfsh
       /usr/bin/sh		  /usr/bin/tcsh
       /usr/bin/zsh		  /usr/xpg4/bin/sh

       The getusershell() function opens the file /etc/shells, if it exists, and returns the next entry in the list of shells.

       The setusershell() function rewinds the file or the list.

       The endusershell() function closes the file, frees any memory used by getusershell() and setusershell(), and rewinds the file /etc/shells.

RETURN VALUES

       The getusershell() function returns a null pointer on EOF.

BUGS

       All information is contained in memory that may be freed with a call to endusershell(), so it must be copied if it is to be saved.

SunOS 5.10							    30 Aug 2004 						  getusershell(3C)
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