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Full Discussion: shell variables advanced
Top Forums Shell Programming and Scripting shell variables advanced Post 302338756 by edidataguy on Tuesday 28th of July 2009 09:11:22 PM
Old 07-28-2009
Quote:
Originally Posted by wakatana
Hi all, i have more questions but its all about variables so lets begin

1st, is possible to list all variables ?
Command env display only shell variables, but what if i declared another variable? Command set display more variables but not defined by me.

2nd, what difference is between set and env ?

3rd, lets say i declared variable which contains whitespaces, or i have variable which contains whitespaces for example IFS. When i type echo $IFS i see nothing, so i dont know if is declared or if contain white spaces.
Is possible to write white spaces in C format (\n \r \t ...) ?

4th what is difference between sourcing and exporting variable ?
PS: i saw declaration of IFS in set command (IFS=$' \t\n')
1. "set" lists all variables. Double check, your variable must be there.
Try this:
Code:
 
aassdd="blabla" (or set aassdd="blabla")
echo $aassdd
set | grep aassdd

2. "env" list all environment variables.

3. For variable with space use quotes.
Code:
 
    qq="aaa                  vvv"
    echo $qq       # output will be ==> aaa vvv
    echo "$qq"     # output will be ==> aaa                  vvv

4. For $IFS do the same as before:
Code:
 
    set | grep "$IFS"

 

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LEARN ABOUT SUSE

tcp-env

tcp-env(1)                                                    General Commands Manual                                                   tcp-env(1)

NAME

       tcp-env - set up TCP-related environment variables

SYNOPSIS

       tcp-env [ -rR ] [ -ttimeout ] program [ arg ...  ]

DESCRIPTION

       The  input  for  tcp-env  must be a TCP connection.  tcp-env finds out information about that connection, puts the information into several
       environment variables as described in tcp-environ(5), and runs program with the given arguments.

       Usually tcp-env is run from inetd.  It might instead be run from another server that already sets up the right  environment  variables;  if
       PROTO  is  set  to  TCP  when  tcp-env  is invoked, tcp-env assumes that all the other variables are set up properly, and it does not check
       whether the input is a TCP connection.

OPTIONS

       -r     (Default.)  Attempt to obtain TCPREMOTEINFO from the remote host.

       -R     Do not attempt to obtain TCPREMOTEINFO from the remote host.

       -ttimeout
              Give up on the TCPREMOTEINFO connection attempt after timeout seconds.  Default: 30.

SEE ALSO

       tcp-environ(5), inetd(8)

                                                                                                                                        tcp-env(1)
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