BA SH REFERENCE
A li
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si
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.6
A r
i
thme
ti
c Eva
l
ua
ti
on.
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8
A r
r
a
y
s .
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1
3
Br
a
c
e
Expansi
on.
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6
Bui
l
t-
In
Comma
nds .
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1
6
Comma
nd
Li
ne
A r
g
uments .
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3
Comma
nd
Substitution.
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8
Conditi
ona
l
Expr
e
ssi
ons .
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1
5
Contr
ol
Comma
nds .
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1
4
Def
initi
ons .
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.2
Executi
on
Or
der.
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1
3
Fi
e
ld Spl
i
tti
ng.
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8
Func
ti
ons .
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1
2
H i
stor
y
Substitution.
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5
I
nput/
Output .
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1
3
I
nvoca
ti
on a
nd
Sta
rtup
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.3
Job
I
ds a
nd
Job
Contr
ol.
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24
Options Tose
t.
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22
Options Tos hopt.
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23
Options Tote
st.
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21
Pa
tte
r
ns .
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.9
Pre
-
Def
i
ned
Va
r
ia
bl
e
s
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1
0
Proce
ss Substitution .
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8
Prompting
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.4
Quoti
ng
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.6
Re
a
dli
ne
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25
Re
a
dli
ne
Dir
e
ctive
s .
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25
Re
a
dli
ne
Ke
y
Bi
ndi
ng
s .
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25
Re
a
dli
ne
Va
r
ia
bl
e
s
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26
Re
str
i
c
te
dba
sh.
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2
Sig
na
ls a
nd
Tr
a
ps .
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1
3
Sp
e
ci
a
l
Cha
r
a
c
te
r
s.
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24
Ti
l
de
Substitution.
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6
Va
r
ia
bl
e
Assi
g
nment.
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9
Va
r
ia
bl
e Na
me
s .
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9
Va
r
ia
bl
e
Substitution .
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7
CONTEN TS
Th
i
s re
f
erence ca
r
d
w a
s
w r
i
tten by
A r
nol
d Robbi
ns.
W e
th
a
nk
Che
t Ra
me
y
(
ba
sh’
s
ma
i
nta
i
ner
)
f
or h
i
s h
e
l
p.
Speci
a
l
i
zedSy
stems Cons ulta
nts,
I
nc.
(
20
6)FOR-
UNI
X/
(
20
6)
7
82-
7
7
33
FAX:
(
20
6)
7
82-
7
1
9
1
E-
ma
i
l
:
sa
l
e
s@ ssc.
com
URL:
h
t
t
p:
/
/
w w w.
ssc.
com
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nux
Jour
na
l
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e
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mi
e
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g
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CDs
SA MBA :
I
nteg
r
a
ting UNIX a
nd
W i
ndow s
Sh
ell
Tutor
ia
l
s,
KSH
Ref
erence
VI
&
Emacs
Ref
erences,
VI
Tutor
ia
l
OTHER S S C PRODUCTS:
© Copy
r
i
g
ht 1
9
9
9
Speci
a
l
i
zed Sy
ste
ms
Cons ulta
nts,
I
nc.
,
P
.
O.
Box
55549
,
Se
a
ttle
,
W A 9
81
55-
0
549
.
A l
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Ri
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Re
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1
Th
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A SCI
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rti
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the entir
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the
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The
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r
e
:
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t th
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st substitution
H I
STORY SUBSTI
TUTI
ON
5
\
c
quote
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ng
l
e
ch
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r
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te
rc
`
.
.
.
`
ol
d s ty
l
e comma
nd
s ubstitution
"
.
.
.
"
te
x
t tr
e
a
te
d
a
s a
si
ng
l
e
a
r
g
ument,
doubl
e
quote
s
re
move
d;
v
a
ri
a
bl
e
,
c
omma
nd and
a
rithme
ti
c substitutions per
f
ormed;
use\to quote$
,
\
,
`
,
a
nd"
$
"
.
.
.
"
l
i
k
e"
.
.
.
"
,
but loca
le
tra
nsla
ti
on done
´
.
.
.
´
te
x
t tr
e
a
te
d
a
s a
si
ng
l
e
a
r
g
ument,
si
ng
l
e
quote
s re
move
d;
te
x
t
betw e
e
n quotes
l
e
f
t
a
l
one,
c
a
nnot
i
nclude´
$
´
.
.
.
´
te
x
t tr
e
a
te
d
a
s a
si
ng
l
e
a
r
g
ument,
$
a
nd
si
ng
l
e quote
s re
move
d;
no
s ubstitutions
per
f
ormed;
A N SI
C
a
nd additi
ona
l
e
sca
pe
se
quenc
e
s
proce
ssed:
\
a
a
l
e
r
t(
be
l
l
)
\
v
vertic
a
lta
b
\
b
ba
ck
spa
ce
\
ddd
octa
l
va
lueddd
\
f
f
or
m
f
e
e
d
\
xh
h
h
h
e
x
va
l
ueh
h
h
\
n
new l
i
ne
\
\
ba
ck
sla
sh
\
r
ca
r
r
i
a
g
e
r
e
tur
n
\
e
e
sca
pe,
not i
n A N SI
C
\
t
h
oriz
onta
l ta
b
QUOTI
NG
a
li
a
s na
me
=va
l
ue.
.
.
A l
i
a
se
s a
r
e
e
x
panded
w hen a
comma
nd
i
s re
a
d,
not
w h
e
n e
x
ecute
d.A li
a
s na
me
s ca
n conta
i
n a
ny
non-
speci
a
l
c
h
a
r
a
c
te
r,
not j
us t a
lpha
nume
ri
cs,
e
x
ce
pt f
or=.
A li
a
s e
x
pansi
on
i
s done on
the
f
irstw o
r
dof
a comma
nd.
I
f
the
l
a
st c
h
a
r
a
c
ter of th
e
r
e
pl
a
c
e
ment te
x
t is
abl
a
nk
,
then
th
e
nex
t
w ord
i
n
the
comma
nd
l
i
ne
i
s ch
eck
e
d
f
or
a
li
a
s e
x
pansi
on.
A li
a
se
s ca
n even be use
d
to rede
f
i
ne
sh
el
l
k
ey
w or
ds ,
but
not in POSI
X
mode.
ALI
A SI
NG
Br
a
c
e
e
x
p
a
nsi
on i
s si
mi
l
a
r to csh
’
s.A w ord must
conta
i
n a
t le
a
st
one unquote
d
le
f
t
br
a
c
e
a
nd comma
to
be expanded.ba
sh expands the comma
-
se
pa
r
a
te
d
ite
ms i
n or
der
,the resu
lt i
s not sorte
d
.
Bra
c
e
e
x
pansi
ons
ma
y
be nested.
For
e
x
a
mpl
e
:
$
mk
dir /
usr/
{
gnu,
loca
l}/
{sr
c
,
bin,
lib}
BRA CE EXP
A NSI
ON
˜
s ubstitute$
H OME
˜
u
se
r
s ubstituteu
se
r
’
s h
ome dir
e
ctory
˜
+
s ubstitute$
PW D
s ubstitute$
OLD PW D
˜
n
s ubstitute$
{
DI
RSTA CK[
n
]
}.A lea
di
ng+
or
i
s a
ll
ow ed:
ne
g
a
tive va
l
ues count
f
r
om
the end of
the
sta
c
k
Ti
lde
s ubstitution h
a
ppens a
f
te
r
a
li
a
s e
x
pansi
on.I
t
i
s
done f
or w ords th
a
t beg
i
n w ith ˜a
nd f
or
va
r
ia
bl
e
a
ssi
g
nment.
I
n va
r
ia
bl
e
a
ssi
g
nments,
it i
s a
lso
done
af
te
r
a:i
n
the
va
l
ue.
Ti
l
de s ubstitution i
s done
a
s pa
r
t of w ord
e
x
pansi
on.
Th
i
s
me
a
ns
f
or$
{
na
me
op
w o
r
d
},
w o
r
dw i
l
l
be
check
ed
f
or ti
l
de
s ubstitution,
but onl
y
i
f
th
e
oper
a
ti
on
requ
ir
e
s
th
e
va
lue of
the
r
ig
ht-
h
a
nd
si
de.
TI
LDE
SUBSTI
TUTI
ON
6
$
na
me
reference
to sh
e
l
l
va
r
ia
bl
ena
me
$
{
na
me
}
us e
br
a
c
e
s to deli
mit
sh
el
l
va
r
ia
bl
ena
me
$
{
na
me w o
r
d
}
us e va
r
ia
bl
ena
mei
f
se
t,
e
l
se
usew o
r
d
$
{
na
me
=w o
r
d
}
a
s a
bove but a
lso se
tna
metow o
r
d
$
{
na
me
?w o
r
d
}
usena
mei
f
se
t,
oth
e
rw i
se
pr
intw o
r
da
nd
e
x
it (
inte
r
a
c
ti
ve
sh
ell
s do not e
x
it)
$
{
na
me
+w o
r
d
}
usew o
r
di
fna
mei
s se
t,
oth
e
rw i
se
use
nothi
ng
$
{
na
me
[
n
]}
e
l
e
mentni
n a
r
r
a
yna
me
$
{
#
na
me
}
l
eng
th
of
sh
el
l
va
r
ia
bl
ena
me
$
{
#
na
me
[
*
]
}
number of e
le
ments
i
n a
r
r
a
yna
me
$
{
#
na
me
[
@]
}
number of e
le
ments
i
n a
r
r
a
yna
me
$
{
na
me
#
p
a
t
}
re
move
sh
or
te
st le
a
di
ng
s ubstr
i
ng
ofna
meth
a
t
ma
tch
e
s p
a
t
$
{
na
me
#
#
p
a
t
} re
move
l
ong
est
l
e
a
di
ng
s ubstr
i
ng
ofna
meth
a
t
ma
tch
e
s p
a
t
$
{
na
me
%p
a
t
} re
move
sh
or
te
st tr
a
i
l
i
ng
s ubstr
i
ng
ofna
meth
a
t
ma
tch
e
s p
a
t
$
{
na
me
%%p
a
t
}
re
move
l
ong
est tr
a
i
l
i
ng
s ubstr
i
ng
ofna
meth
a
t
ma
tch
e
s p
a
t
$
{
na
me
:
sta
r
t
}
$
{
na
me
:
sta
r
t
:
l
e
ng
th
}
l
e
ng
thc
h
a
r
a
c
te
r
s ofna
mesta
r
tinga
t
sta
r
t(
counting
f
r
om 0
)
;
us e
r
e
st of
va
l
ue
i
f
nol
e
ng
th
.
N e
g
a
tivesta
r
t
counts f
r
om
the end.
I
fna
mei
s *or@
or a
n a
rra
y
i
nde
x
ed by*or@,
sta
r
t
a
ndl
e
ng
thi
ndi
ca
te
th
e
a
r
r
a
y
i
nde
x
a
nd
count
of
e
l
e
ments.
sta
r
ta
ndl
e
ng
thc
a
n
be a
r
i
thme
ti
c
e
x
pr
e
ssi
ons
$
{
na
me
/
pa
tte
r
n
/
str
i
ng
}
va
l
ue ofna
mew ith
f
ir
st
ma
tch ofpa
tte
r
n
repl
ace
d
w ithstr
i
ng
$
{
na
me
/
pa
tte
r
n
}
va
l
ue ofna
mew ith
f
ir
st
ma
tch ofpa
tte
r
n
del
e
te
d
$
{
na
me
/
/
pa
tte
r
n
/
str
i
ng
}
va
l
ue ofna
mew ith
e
ver
y
ma
tch of
pa
tte
r
n r
epl
ace
d
w ithstr
i
ng
$
{
na
me
/
#
pa
tte
r
n
/
str
i
ng
}
va
l
ue ofna
mew ith
ma
tch ofpa
tte
r
n
repl
ace
d
w ithstr
i
ng
;ma
tch
mus t occur
a
t
beg
i
nni
ng
$
{
na
me
/
%pa
tte
r
n
/
str
i
ng
}
va
l
ue ofna
mew ith
ma
tch ofpa
tte
r
n
repl
ace
d
w ithstr
i
ng
;ma
tc
h
occurs
a
t e
nd
Note
:f
or ,=,?,a
nd +
,usi
ngna
me
:i
nste
a
d ofna
me
te
sts
w h
etherna
mei
s se
t a
nd non-
NULL;
usi
ngna
me
te
sts onl
y
w h
etherna
mei
s se
t.
For#
,
#
#
,
%,
%%,
/
,
/
/
,
/
#
,
a
nd/
%,
w hen na
mei
s *or@
or a
n a
rra
y
i
nde
x
ed by * or @,the s ubstr
i
ng
or
s ubstitution oper
a
ti
on
i
s a
ppl
i
ed
to e
a
c
h
e
l
ement.
VA RI
A BLE SUBSTI
TUTI
ON
7
A r
i
thme
ti
c eva
l
ua
tion i
s done w ith the let bui
l
t-
i
n
comma
nd,
the (
(
.
.
.
)
) comma
nd and the $
(
(
.
.
.
)
)
e
x
pansi
on
f
or produci
ng
the
r
e
sult
of
a
n e
x
pr
e
ssi
on.
A l
l
a
rithme
ti
c use
s longi
nte
g
e
rs.
Use
to g
e
t
i
nte
g
e
r va
ri
a
bl
e
s.I
nte
g
e
r consta
nts
l
ook
li
k
e
[
ba
se
#
]
n
w h
er
eba
sei
s a
deci
ma
l
number
betw e
e
n
tw o a
nd
64,
a
ndn i
s
i
n
th
a
t
ba
se
.
The di
g
its a
r
e0
-
9
,
a
-
z,
A -
Z,
_a
nd
@.
A l
e
a
di
ng0or0
xdenote octa
l
or h
e
x
a
deci
ma
l
.
The
f
oll
ow i
ng
oper
a
tors b
a
sed on C,
w ith the
sa
me
precedence and associ
a
ti
vity
,
a
re ava
i
la
bl
e.
una
ry
pl
us a
nd
mi
nus
!˜
l
og
i
ca
l
a
nd bitw i
se
ne
g
a
tion
*
*
e
x
ponentia
ti
on
(
not i
n C)
*/
%
multi
pl
y
,
di
vi
de,
modul
us
additi
on,
subtr
a
ction
<< >>
l
e
f
t
s h
i
f
t,
r
i
g
ht shi
f
t
< <= > >=
compa
r
isons
== !
=
equa
ls,
not equa
l
s
&
bitw i
se
A N D
ˆ
bitw i
se
XOR
|
bitw i
se
OR
&&
l
og
i
ca
l
A N D,
sh
or
tcir
cui
t
|
|
l
og
i
ca
l
OR,
sh
or
tcir
cui
t
?:
i
n-
l
i
ne
conditi
ona
l
a
ssi
g
nment ope
r
a
tors
I
nsi
delet,
(
(
.
.
.
)
)
,
a
nd$
(
(
.
.
.
)
)
,
va
r
ia
bl
e
na
me
s
do not
need
a$
to g
e
t th
e
i
r
va
l
ues.
A RI
TH METI
C EVALUATI
ON
$
(
comma
nd
) new
f
or
m
`
comma
nd
`
ol
d
f
or
m
Run comma
nd,s ubstitute
the r
e
sults a
s a
r
g
uments.
Tra
i
l
i
ng
ne
w li
nes a
re re
move
d.
Cha
r
a
c
te
r
s i
n $
IFS
se
pa
r
a
te
w or
ds (
se
eFi
el
d Spl
i
t
t
i
ng
)
.
Th
enew
f
orm
i
s
pr
e
f
e
r
r
e
d
f
o
r
simpler quoti
ng
r
ul
e
s.
$
(
(
e
x
pr
e
ssi
on
)
)a
rithme
ti
c substitution
Th
ee
x
pr
e
ssi
on i
s eva
lua
ted,
a
nd th
e
result is used a
s a
n
a
rg
ument to th
e
curre
nt comma
nd.
COMMA ND SUBSTI
TUTI
ON
cmd
<(
l
i
st1
)>(
l
i
st2
)
Runs l
i
st1a
nd l
i
st2 a
sy
nchronous ly
,w ith stdin a
nd
stdout r
e
specti
ve
l
y
conne
cte
d
vi
a
pi
pes usi
ng
f
i
f
os or
f
i
l
e
s
i
n /
dev/
f
d.
Th
ese
f
i
l
e na
me
s
become
a
r
g
uments to
cmd,
w hi
c
h
e
x
pects to re
a
d
its f
i
r
st
a
rg
ument a
nd
w r
i
te
its second.
Th
i
s onl
y
w ork
s
i
f
y
ou h
a
ve/
dev/
f
do
r
f
ifos.
PROCESS SUBSTI
TUTI
ON
Quoted te
x
t become
s one w ord. Oth
er
w i
se
,
occur
r
ences of
a
ny
c
h
a
r
a
c
te
r
i
n $
IFS se
pa
r
a
te
w ords.
Multi
pl
e
w hite
spa
c
e
ch
a
r
a
c
te
r
s th
a
t a
r
e
i
n $
IFS do not
del
i
mit e
mpty
w ords,
w hi
l
e
multi
pl
e non-
w hite
spa
ce
c
h
a
r
a
cte
r
s do.W hen $
IFS i
s not the def
a
ult va
lue,
se
quences of
le
a
di
ng
a
nd tr
a
i
l
i
ng $
IFS w hite
spa
ce
c
h
a
r
a
c
te
r
s a
re re
moved,
a
nd pr
inta
bl
e ch
a
r
a
c
te
r
s i
n
$
IFS
s ur
r
ounded by
a
dj
ace
nt $
IFS
w hite
spa
ce
c
h
a
r
a
cte
r
s
deli
mit f
i
e
lds.I
f$
IFS i
s NULL,ba
shdoes
not
do
f
i
e
l
d s pli
tti
ng
.
FI
ELD SPLI
TTI
NG
8
?
ma
tch
si
ng
l
e
ch
a
r
a
c
te
r
i
n
f
i
l
ena
me
*
ma
tc
h
0
or
more
c
h
a
r
a
c
te
r
s
i
n
f
i
l
e
na
me
[
c
h
a
r
s
]
ma
tch
a
ny
ofc
h
a
r
s
(
pa
i
r
se
pa
r
a
te
d
by
a ma
tch
e
s a
rang
e
)
[
!
c
h
a
r
s
]
ma
tch
a
ny
e
x
ce
ptc
h
a
r
s
[
ˆ
c
h
a
r
s
]
ma
tch
a
ny
e
x
ce
ptc
h
a
r
s
I
f
the ex
tg
lob option to s hopt i
s se
t,
the f
ol
l
ow i
ng
e
x
te
nded
ma
tch
i
ng
f
a
ci
l
i
tie
s
ma
y
be use
d.
?(
pa
t
-
l
i
st
)
optiona
l
l
y
ma
tc
h
a
ny
of
the pa
tterns
*
(
pa
t
-
l
i
st
)
ma
tc
h
0
or
more
of
a
ny
of
the pa
tterns
+
(
pa
t
-
l
i
st
)
ma
tc
h
1
or
more
of
a
ny
of
the pa
tterns
@(
pa
t
-
l
i
st
)
ma
tch
e
x
a
ctly
1
of
a
ny
of
the pa
tterns
!
(
pa
t
-
l
i
st
)
ma
tch
a
ny
thi
ng but a
ny
of
the pa
tterns
pa
t
-
l
i
sti
s a
l
i
st
of
one or
more
p
a
tterns se
p
a
r
a
ted by|
.
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e
P
OSI
X [
[
=c=]
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nd[
[
.
c
.
]
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ti
ons for sa
me
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w e
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c
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r
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a
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le
ments a
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d.Th
e
nota
ti
on [
[
:
cl
a
ss
:
]
]def
i
nes ch
a
r
a
c
te
r
cl
a
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s:
a
lnum
a
l
pha
nume
r
i
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a
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punct
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e
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a
deci
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l
Th
r
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es hoptoptions a
f
f
e
ct
pa
tte
r
n
ma
tch
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ng
.
dotg
lob
i
ncl
ude
f
i
l
e
s
w h
ose
na
me
s
beg
i
n
w ith.
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se
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re
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tte
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ns
th
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t
don’
t
ma
tch
W hen expandi
ng
f
i
l
e
na
me
s,.a
nd .
.a
r
e
i
g
nored,
f
i
l
ena
me
s
ma
tch
i
ng
the pa
tterns
i
n $
G LOBIG N OREa
r
e
a
lso
i
g
nored a
nd a l
e
a
di
ng.
must
be
s uppl
i
ed
i
n
the
pa
ttern to ma
tc
h
f
i
l
ena
me
s th
a
t beg
i
n w ith ..
H ow eve
r
,se
tti
ng G LOBIG N ORE ena
bl
e
s thedotg
lob
option.
I
ncl
ude.
* i
n G LOBIG N ORE to g
e
t th
e
de
f
a
ul
t
b
e
h
a
vi
or
.
P
ATTERNS
Va
r
ia
bl
e
na
me
s a
r
e
made up of
le
tte
r
s,
d
i
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its a
nd
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r
score
s.
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eyma
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not sta
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it.
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er
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i
s
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l
i
mit
on
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l
eng
th
of
a
va
r
ia
bl
e
na
me,
a
nd
the
c
a
se
of
le
tte
r
s
i
s si
g
ni
f
ica
nt.
VA RI
A BLE N A MES
A ssi
g
nments to i
nte
g
e
r va
ri
a
bl
e
s underg
o
a
rithme
ti
c
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l
ua
tion.
Va
ria
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le
a
ssi
g
nments h
a
ve one of
the
f
ol
l
ow i
ng
f
orms.
na
me
=w o
r
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tna
metow o
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d
na
me
[
i
nde
x
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r
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se
t
e
le
menti
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xof
a
r
r
a
yna
metow o
r
d
na
me
=(
w o
r
d.
.
.
)
se
t i
nde
x
ed a
r
r
a
yna
metow ords
na
me
=(
[
num
]
=w o
r
d.
.
.
)
se
t
g
i
ve
n
i
ndi
ces of
a
r
r
a
yna
metow ords
VA RI
A BLE ASSI
G N MEN T
9
$
n
use positi
ona
l
pa
ra
me
te
rn,
n 9
$
{n}
use positi
ona
l
pa
ra
me
te
rn
$
*
a
l
l
positi
ona
l
pa
ra
me
te
r
s
$
@
a
l
l
positi
ona
l
pa
ra
me
te
r
s
"
$
*
"
equi
va
l
ent to"
$
1
$
2 .
.
.
"
"
$
@"
equi
va
l
ent to"
$
1
"
"
$
2".
.
.
$
#
number of positi
ona
l
pa
ra
me
te
r
s
options to sh
el
l
or byse
t
$
?
va
l
ue
r
e
tur
ned by
l
a
st c
omma
nd
$
$
proce
ss
number of current sh
e
l
l
$
!
proce
ss nu
mber
of
la
st ba
ck
g
round
cmd
$
_
na
me
of
pr
og
r
a
m
i
n e
nvir
onment a
t
sta
r
tup. Va
lue of
la
st positi
ona
l
a
r
g
ument in
l
a
st c
omma
nd.
Name of
chang
e
d
ma
i
l
f
i
l
e
i
n $
MA I
LP
ATH
$
a
uto_
r
e
sume
ena
bl
e
s
use
of
sing
l
e
-
w ord
comma
nds to
ma
tc
h
s topped
j
obs
f
or
f
ore
g
roundi
ng
.
W ith
a
va
l
ue ofe
x
a
ct,
the w ord must e
x
a
c
tly
ma
tch the
comma
nd use
d
to sta
rtthe
j
ob.
W ith
ava
l
ue ofs ubstring
,
the
ty
ped
w or
d
ca
n be
a
s ubstr
i
ng
of
the
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nd,
l
i
k
e%?str
i
ng
$
BA SH
f
ul
l
f
i
l
e
na
me use
d
to
i
nvok
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sh
$
BA SH _ENV
i
n norma
l
non-
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nte
r
a
c
ti
ve
sh
e
l
l
s only
,
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l
ue i
s va
r
ia
bl
e
,
comma
nd and
a
rithme
ti
c substituted f
or
pa
th of
sta
r
tup f
i
l
e
(
Se
e I
nvoca
t
i
on And
St
a
r
tup)
$
BA SH _
VERSI
ON
th
e
versi
on ofba
sh
$
BA SH _VERSINFO[
0
]
the ma
j
or versi
on number
(
r
e
l
e
a
se
)
$
BA SH _VERSINFO[
1
]
the mi
nor ve
r
si
on number
(
ve
rsi
on)
$
BA SH _VERSINFO[
2]
the pa
tc
hl
evel
$
BA SH _VERSINFO[
3]
the bui
l
d ve
rsi
on
$
BA SH _VERSINFO[
4]
the
re
le
a
se
sta
tus
$
BA SH _VERSINFO[
5]
sa
me
a
s $
MA CH TYPE
$
CDPATH
se
a
rc
h pa
th forcdcomma
nd
$
DI
RSTA CK[
*
] a
rra
y
va
r
ia
ble conta
i
ni
ng
the pus h
d
a
ndpopddir
e
ctory
sta
c
k
$
EN V
i
n
i
nte
r
a
c
ti
ve POSI
X
mode
sh
ell
s,
or
w hen
i
nvok
ed a
s sh
,
va
l
ue
i
s va
r
ia
bl
e,
comma
nd and
ar
i
t
hme
tic substitute
d
f
or pa
th
of
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rtup
f
i
le
$
EUI
D
th
e
ef
f
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id
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e
a
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y
)
$
FCED I
T
def
a
ult
edito
r
f
o
r
thef
ccomma
nd
(
no
def
a
ult
va
l
ue)
$
FI
G N ORE
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se
pa
r
a
te
d
l
i
st
of
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f
i
x
e
s g
i
vi
ng
the
se
t
of
f
i
le
na
me
s
to i
g
nor
e
w hen
doi
ng
f
i
l
e
na
me compl
e
ti
on usi
ng
r
e
a
dline
$
G LOBIG N ORE colon-
se
pa
r
a
te
d
li
st
of
pa
tterns g
i
vi
ng
the
se
t
of
f
i
le
na
me
s
to i
g
nor
e
w hen
doi
ng
pa
tte
r
n
ma
tchi
ng
$
G ROUPS[
*
]
readonly
a
rra
y
va
r
ia
bl
e
w ith
the
l
i
st
of
g
roups th
e
u
ser be
l
ong
s to
$
histc
h
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rs
c
h
a
r
a
c
te
r
s th
a
t contr
ol csh
-
sty
l
e
hi
story
(
def
a
ult: !
ˆ
#
)
.
Se
e H i
st
or
y
Subst
i
t
ut
i
on
PRE-
DEFI
N ED
VA RI
A BLES
1
0
$
H I
STCMD
hi
story
number
o
f
the cur
r
ent
comma
nd
$
H I
STCONTROL w ith
a
va
l
ue ofig
nore
spa
ce,do not
ente
r
li
nes th
a
t beg
i
n w ith
s paces
i
nto the h
i
story
f
i
l
e
.W ith
a
va
l
ue of
ig
nore
dups,do not e
nte
r
a
l
i
ne
th
a
t
ma
tch
es the pr
e
vi
ous li
ne. Use
ig
nore
bothto combi
ne both
options
$
H I
STFI
LE
w h
er
e comma
nd h
i
stor
y
i
s store
d
$
H I
STFI
LESIZE ma
x
i
mum
number
o
f
lines to k
e
e
p
i
n
$
H I
STFI
LE
$
H I
STI
G N ORE
col
on-
se
pa
r
a
ted
l
i
st
of
pa
tte
r
ns;
i
f
the
cur
r
ent li
ne
ma
tc
h
e
s a
ny
of
th
em,
the
l
i
ne
i
s not
ente
r
e
d
i
n
the hi
story
f
i
l
e.
& represe
nts th
e
l
a
st hi
story
li
ne.
Pa
tterns
must
ma
tch
the
w h
ole
l
i
ne
$
H I
STSI
ZE
number
of
pr
e
vi
ous comma
nds to
k
e
e
p ava
i
l
a
bl
e
w hi
l
eba
shi
s runni
ng
$
H OME
h
ome
dir
e
ctory
f
orcd comma
nd a
nd
va
l
ue use
d
f
or ti
l
de expansi
on
$
H OSTFILE
f
i
l
e
i
n
f
orma
t of/
e
tc/
h
osts to use
f
or
h
ostna
me compl
e
ti
on
$
H OSTNA ME
na
me
of
the
cur
r
ent
h
ost
$
H OSTTYPE
str
i
ng
de
scr
ibi
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the
cur
r
ent
h
ost
$
IFS
f
i
e
l
d s epa
r
a
tors
(
spa
c
e
,
ta
b,
new line
)
$
I
G N OREEOF
f
or
i
nte
r
a
c
ti
ve sh
e
l
ls,
the number
of
consecutive EOFs th
a
t must be
entered be
f
or
eba
sha
ctua
l
l
y
e
x
its
$
I
NPUTRC
na
me of r
e
a
dline sta
r
tup
f
i
l
e,
ove
r
r
i
des ˜
/
.
inputrc
$
LA N G
na
me
of
c
ur
r
ent loca
l
e
$
LC_ALL
cur
r
ent
loca
le
;
o
v
e
r
ri
des $
LA N G a
nd
oth
e
r$
LC_va
r
ia
bl
es
$
LC_COLLATE
cur
r
ent
loca
l
e
f
or ch
a
r
a
c
ter col
l
a
ti
on,
i
ncl
ude
s sor
ti
ng
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lts of
f
i
l
e
na
me
e
x
pansi
on
$
LC_CTYPE
cur
r
ent loca
l
e
f
or ch
a
r
a
c
te
r
cla
ss
f
unc
ti
ons (
se
ePa
t
t
er
ns)
$
LC_
MESSA G ES cur
r
ent l
oca
le
f
or tra
nsla
ti
ng $
"
.
.
.
"
str
i
ng
s
$
LINENO
l
i
ne number
of
li
ne bei
ng
e
x
e
cuted
i
n
scr
ipt or f
unc
ti
on
$
MA CH TYPE
astr
i
ng
i
n G N U cpu-
compa
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-
sy
ste
m
f
or
ma
t de
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bi
ng
the ma
chi
ne
r
unni
ngba
sh
$
MA I
L
na
me
of
a
ma
i
l
f
i
l
e
,
i
f
a
ny
$
MA I
LCHECK
check
f
or ma
i
l
eve
r
y n seconds (
60
def
a
ult)
$
MA I
LP
ATH
f
i
l
e
na
me
s
to ch
eck
f
or ne
w ma
i
l
;
uses
:se
pa
r
a
tor;f
i
l
e
na
mema
y
be
f
ol
l
ow e
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by ?me
ssa
g
e
; $
_ i
n
me
ssa
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e i
s
ma
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i
l
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i
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na
me
.Over
r
i
des
$
MA I
L
$
OLD PW D
pr
e
vi
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ng
dir
e
ctory
$
OP
TA RG
va
l
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l
a
st a
r
g
ument
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sse
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etopts
$
OPTERR
i
f
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,
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s pl
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ssa
g
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f
r
om g
etopts (
de
f
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)
$
OPTIND
i
nde
x
of
l
a
st a
rg
ument
proce
sse
d by
g
etopts
PRE-
DEFI
N ED
VA RI
A BLES
(
continued)
1
1
$
OSTYPE
str
i
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de
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i
bi
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the
oper
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ti
ng
sy
ste
m r
unni
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ba
sh
$
PATH
comma
nd
se
a
rc
h pa
th
$
PI
PESTATUS[
*
]
a
rra
y
va
r
i
a
bl
e conta
i
ni
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e
x
i
t
sta
tus va
l
ues f
r
om
proce
sse
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i
n
the
most r
ece
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f
ore
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round pi
peli
ne
$
PPI
D
proce
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el
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PROMPT_
COMMA N D
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un be
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ore
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a
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ima
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PS1
pr
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(
)
$
PS2
seconda
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>)
$
PS3
se
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nd pr
ompt
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(
#
?)
$
PS4
tr
a
ci
ng
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(
+
)
$
PW D
cur
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w ork
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ctory
$
RA N DOM
se
t e
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it’
s referenced,
$
REP
LY
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lect a
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e
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$
S ECONDS
numbe
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$
SH ELL
na
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$
SH ELLOPTS
col
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se
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ra
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d
l
i
st of
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e
l
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$
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i
ncre
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f
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TI
MEFORMA T
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orma
t stri
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or outpu
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Sp
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[
l]
R
el
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[
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U
us er
CPU secs
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[
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CPU perc
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ter
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Optiona
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ci
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its a
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te
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th
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ma
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nt;
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a
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i
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FF
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$
TMOUT
number of seconds to w a
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ing
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ting
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UI
D
the
r
e
a
l
us er
i
d
(
r
e
a
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PRE-
DEFI
N ED
VA RI
A BLES
(
cont
i
nued)
Func
ti
ons run
i
n
the
sa
me proce
ss a
s
the
ca
l
l
i
ng
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ipt,
a
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a
r
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f
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r
ent
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c
c
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pa
ra
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1
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on.
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0doe
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re
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y
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i
nsi
de
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ti
on or .scr
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Func
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a
r
e
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i
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e
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nf
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h
orizonta
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di
s pl
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ons h
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onta
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,w ith
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a
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mbig
uous (
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i
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i
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ns te
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sta
ts (
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w hen li
sti
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REA DLI
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A BLES
Mor
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e
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n be
f
ound on-
l
i
ne
a
t
http:
/
/
w w w .
ssc
.
c
om/
ssc/
ba
sh
.
26
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