*** bash - 2005-09-20 *** 

EXPANSIONS
==========
Brace expansion
--------------
{b,c}d is expanded to abd acd
(note: brace: { }, square bracket: [ ], parenthesis: ( ) )

examples:
root@dolphin:~/test# echo E-mail: {Smith,Tailor}@ieee.org
E-mail: Smith@ieee.org Tailor@ieee.org
--
root@dolphin:~/test# echo lencse@{{mail,rs1}.,""}{szif,sze}.hu
lencse@mail.szif.hu lencse@mail.sze.hu lencse@rs1.szif.hu lencse@rs1.sze.hu lencse@szif.hu lencse@sze.hu

Tilde expansion
---------------
~lencse/public_html 

examples:
root@dolphin:~/test# cd ~lencse
root@dolphin:/home/lencse#
--
root@dolphin:~/test# lynx http://dolphin.szif.hu/~lencse

Parameter Expansion
-------------------
$parameter or ${parameter}

example:
root@dolphin:~# alma=apple
root@dolphin:~# echo $alma
apple

Command Substitution
--------------------
$(command) or `command` 
examples:
root@dolphin:~/test# ls
11  111  121  131
root@dolphin:~/test# rm `ls`
root@dolphin:~/test# ls
root@dolphin:~/test#
--
something more useful is: rm `find -name core`
--
root@dolphin:~# echo "1. sor" > probafile
root@dolphin:~# echo "2. sor" >> probafile
root@dolphin:~# echo `cat probafile`
1. sor 2. sor
-- explanation: see word splitting
root@dolphin:~# echo `< probafile`
1. sor 2. sor
root@dolphin:~# echo "`< probafile`"
1. sor
2. sor

Arithmetic Expansion
--------------------
$((expression))

examples:
lencse@dolphin:~$ echo $((12*3))
36
root@dolphin:~/test# echo $((2**(2,3)))
8
root@dolphin:~/test# echo $((2!=(a=3)))
1
(note: Arithmetic Evalution is done in long integers, operator precedence: C)

Word Splitting
--------------
IFS default is <space><tab><newline>

example, unlike in the earlier example:
root@dolphin:~# echo E-mail:{Smith,Tailor}@ieee.org
E-mail:Smith@ieee.org E-mail:Tailor@ieee.org

Pathname Expansion
------------------
(note: the joker characters are different from the joker characters of the regular expressions)

*, ?, []
 special: starting dot, slash : matched explicitly

examples:
root@dolphin:~/test# ls 1*1
11  111  121  131
root@dolphin:~/test# ls 1[1,2]1
111  121
root@dolphin:~/test# ls 1[2-3]1
121  131
root@dolphin:~/test# ls 1[^2]1
111  131
--
root@dolphin:~/test# echo "one" > 1
root@dolphin:~/test# echo "dot one" > .1
root@dolphin:~/test# echo "ones" > 11
root@dolphin:~/test# ls *
1  11
root@dolphin:~/test# ls ?1
11
root@dolphin:~/test# ls .1
.1

lencse@vip:~/ta65$ echo "three ones" >111
lencse@vip:~/ta65$ mkdir 1
lencse@vip:~/ta65$ echo "file 'one' in the directory 'one'">1/1
lencse@vip:~/ta65$ ls 1?1
111
lencse@vip:~/ta65$ ls 1/1
1/1


Quote Removal
-------------
\, ', " are removed (if they are unquoted/unescaped)
(note: ' - single quote, " - double quote, / - slash, \ - backslash ) 
escape character '\' can be used...

examples:
root@dolphin:~/test# echo test\1 'test2' "test3"
test1 test2 test3
root@dolphin:~/test# echo test\\1 test\'2 test\"3
test\1 test'2 test"3

lencse@vip:~/ta65$ echo "'"
'
lencse@vip:~/ta65$ echo '"'
"


REDIRECTION
===========
Standard I/O/Error: 0, 1, 2 file decriptors
<, >, 
2>&1 
|
>>
<<[-]
examples:
lencse@dolphin:~$ ls -l egyik masik
-rw-r--r--    1 lencse   users          20 Sep 15 19:01 egyik
----------    1 lencse   users          20 Sep 15 19:01 masik
lencse@dolphin:~$ cat egyik masik
egyik file tartalma
cat: masik: Permission denied
lencse@dolphin:~$ cat egyik masik 2>/dev/null
egyik file tartalma
lencse@dolphin:~$ cat egyik masik 1>x
cat: masik: Permission denied
lencse@dolphin:~$ cat x
egyik file tartalma
lencse@dolphin:~$ cat egyik masik 1>x 2>&1
lencse@dolphin:~$ cat x
egyik file tartalma
cat: masik: Permission denied
root@dolphin:~/test# ls
11  111  121  131
root@dolphin:~/test# ls | sort -r
131
121
111
11
root@dolphin:~/test# ps -aux | grep ps
root       336  0.0  0.3  2560  828 tty2     R    20:41   0:00 ps -aux
root       337  0.0  0.1  1328  452 tty2     S    20:41   0:00 grep ps
--
root@dolphin:~/test# echo 1st line > file
root@dolphin:~/test# echo 2nd line >> file
root@dolphin:~/test# cat file
1st line
2nd line
root@dolphin:~/test#
--
lencse@dolphin:~$ cat <<EOF
> 1st line
> 2nd line
> last line
> EOF
1st line
2nd line
last line
lencse@dolphin:~$
--
root@dolphin:~/test# cat test
cat <<- EOF
        an indented line
EOF
root@dolphin:~/test# ./test
an indented line

ALIASES
=======
alias, unalias

examples:
lencse@dolphin:~$ alias
alias d='dir'
alias dir='/bin/ls $LS_OPTIONS --format=vertical'
alias ls='/bin/ls $LS_OPTIONS'
alias v='vdir'
alias vdir='/bin/ls $LS_OPTIONS --format=long'

CONDITIONAL EXPRESSIONS
=======================
[ is a symbolic link to the 'test' command
- file attribute check
- string or arithmetic comparison

examples:
  if [ -x /sbin/quotacheck ]; then
    echo "Checking filesystem quotas:  /sbin/quotacheck -avug"
    /sbin/quotacheck -avug
  fi


BASH kezelese
=============
CRSR up/down
TAB (1st pos, other pos...) recall: PATH 
Ctrl-R
!

JOB CONTROL 
===========
suspend
fg %1
bg %1
(% and its name [prefix] can be used too)
%% or %+ last job
%- previos job

PROMPTING
=========
PS1 primary prompt
PS2 more imput is needed to complete the command

examples:
lencse@mmws:~$ PS1="szeretlek kedvesem! "
szeretlek kedvesem! PS1='\u@\h:\w\$ '
lencse@mmws:~$
The normal prompt is restored.
where:<user>@<host>:<working directory><prompt jel>
see the manual for more special characters

inditaskori parancsfile-ok
--------------------------

Ha a bash egy interaktiv login shell (pl. mikor belepek egy gepre), akkor:
Eloszor, ha van, akkor vegrehajtja
/etc/profile
Utana ebben a sorrendben probalva az elsot (ami letezik es vegrehajthato)
~/.bash_profile, ~/.bash_login, and  ~/.profile
A user altal kiadott parancsok bekerulnek:
~/.bash_history
Ha a bash login shell, mikor kilep, vegrehajtja:
~/.bash_logout
Interaktiv, de nem login shell:
~/.bashrc
Nem interaktiv shell:
BASH_ENV-et kifejti, es azt hasznalja file-nevkent, de nem hasznalja a PATH-t...


Fontosabb kornyezeti valtozok:
-----------------------------
1. amiket a bash hasznal:
IFS
PATH
HOME
MAIL/MAILCHECK/MAILPATH
PS1, 2, (3,4)
HISTORY, HISTSIZE
HISTFILE, HISTFILESIZE

2. amiket beallit 
PWD, OLDPWD
UID, EUID
HOSTNAME

for more, see: Shell Variables