shell "set" and environment variables
If you type set at a Bash prompt you should see
something
like the
following on your vt. These are your current environment variables and
thier values.
BASH=/bin/bash
BASH_VERSION=1.14.7(1)
COLUMNS=80
EDITOR=pico -z
EUID=0
HISTFILE=/root/.bash_history
HISTFILESIZE=500
HISTSIZE=500
HOME=/root
HOSTNAME=BigBroot
HOSTTYPE=i386
.
.
.
.
Every unix process has an "environment". It's environment is the variables
that are visible to it. A shell is a process. The Bash builtin
command set will display all the variables know to the shell.
##########################
Here's the same thing, but the whole thing, the way mine is at the moment,
with some annotation.......
BASH=/bin/bash
The full pathname of your Bash shell.
BASH_VERSION=1.14.7(1)
The version of Bash.
COLUMNS=80
your terminal's width in characters.
EDITOR=pico -z
A default editor, pico with ^z background switch enabled.
EUID=0
Effective user ID. 0 is the superuser. 0 has all permissions.
HISTFILE=/root/.bash_history
what you've been doing in Bash. Do history at a prompt.
HISTFILESIZE=500
size of history ring buffer in lines.
HISTSIZE=500
HOME=/root
where ~ is an alias for, your home directory.
HOSTNAME=BigBroot
Name of the box. See /etc/HOSTNAME
HOSTTYPE=i386
HUSHLOGIN=FALSE
are we disabling the login message of the day?
HZ=100
kernel jiffy clock frequency.
IFS=
input field separator for .e.g. bash read builtin.
LESS=-MM
LESSOPEN=|lesspipe.sh %s
LINES=50
visible lines on your vt.
LOGNAME=root
who you logged in as.
MAIL=/var/spool/mail/root
where your mail is kept. BigBroot doesn't do local mail.
MAILCHECK=60
how often new email is checked for. not applicable.
MINICOM=-c on
OLDPWD=/
your previous working directory. cd - will go there.
OPTERR=1
OPTIND=1
OSTYPE=Linux
a digital penguin. Sharp beak.
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/usr/sbin:/bin:/usr/bin
where the shell looks for commands.
PPID=1
Process ID of the shell's parent process. 1 is init.
PS1=$ /dev/tty1 \u \w \s \t\n$
the usual Bash prompt.
PS2=>
the secondary bash prompt.
PS4=+
PWD=/etc/rc.d
your current directory.
SHELL=/bin/bash
your shell. Bash is 99.44% Bourne script compaqtible, with many
interactive niceties.
SHLVL=1
shells can call shells. How often have we done that?
TERM=linux
Terminal type, from termcap, "linux" is very vt102-like.
UID=0
actual user ID.
USER=root
VISUAL=pico -z
some programs check $VISUAL for what editor you prefer.
_=set
the previous command you executed. I just did set to paste
into this file.
ignoreeof=10
ASCI value of EOF, End Of File, I think. :o)