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# !/bin/csh -vx
#csh -vx show the command before running to help debug

#just to check syntax
#csh -n $0

#argv
if ($ # argv < 2) then
echo " Sorry, but you entered too few parameters "
echo " usage: $0 arg1 arg2
exit
endif
set arg1 = $1
set arg2 = #2

foreach i ($*)
echo $i
end

#execute commands
echo "Hello there `whoami`. How are you today? "
echo "You are currently using `hostname` and the time is `date` "
echo "Your directory is `pwd` "
whoami
hostname
date
pwd

#var
set name = Mark
echo $name
set name = "Mark Meyer " # if the string has space, must use ""
echo $name
# it means set to NULL
set name =
unset name
# get user input
set x = $<
set current_user = `whoami`

#buildin vars
echo $user # who am I?
echo $status # a numeric variable, usually used to retun error codes

#Arithmetic variables
@ i = 2
@ k = ($x - 2) * 4
@ k = $k + 1
@ i--
@ i++

#array
set name = (mark sally kathy tony)
echo $#name # num of the array
echo $name[1]
echo $name[4]
echo $name[2-3]
echo $name[2-] # all elements from 2 to the end
echo $name[1-3]
echo $name[$i]
set name = ($name doran)
set name = (doran $name)
set name = ($name[1-2] alfie $name[3-])
shift name # get rid of the frist element of the array
shift #if no argument is given, it will get rid of argv

#Expressions and operators
== equal (either strings or numbers)
!= not equal (either strings or numbers)
=~ string match
!~ string mismatch
<= numerical less than or equal to
>= numerical greater than or equal to
> numerical greater than
< numerical less than

-e file file merely exists (may be protected from user)
-r file file exists and is readable by user
-w file file is writable by user
-x file file is executable by user
-o file file is owned by user
-z file file has size 0
-f file file is an ordinary file
-d file file is a directory

! -- negate
&& -- logical and
|| -- logical or

#if-else
# run cmd as if expression
if ({grep -s junk $1}) then
echo "We found junk in file $ 1 "
endif
# check if the var is defined
if ($?dirname) then
ls $dirname
endif

if (-e somefile) then
grep $1 somefile
else
echo "Grievous error! Database file does not exist " .
endif

#foreach
foreach i (*)
if (-f $i) then
echo "============= $i =================== "
head $i
endif
if (-d $i) then
(cd $i; headers)
endif
end

#while
while ($#argv > 0)
grep $something $argv[1]
end

@ n = 5
while ($n)
# do something
@ n--
end

#switch-case
switch ($argv[$i])
case quit:
break # leave the switch statement
case list:
ls
breaksw
case delete:
case erase:
@ k = $i + 1
rm $argv[$k]
breaksw
endsw

#here document
grep $i <<HERE
John Doe 101 Surrey Lane London, UK 5E7 J2K
Angela Langsbury 99 Knightsbridge, Apt. K4 Liverpool
John Major 10 Downing Street London
HERE

cat > tempdata <<ENDOFDATA
53.3 94.3 67.1
48.3 01.3 99.9
42.1 48.6 92.8
ENDOFDATA

exit 0

À´×Ô：http://www-cs.canisius.edu/ONLINESTUFF/UNIX/shellprogramming.html

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