integer variables
DESCRIPTION
Integer variables. #!/bin/csh # sum of numbers from $argv[1] to $argv[2] set low = $argv[1] set high = $argv[2] set sum = 0 set current = $low while ( $currentTRANSCRIPT
Integer variables#!/bin/csh
# sum of numbers from $argv[1] to $argv[2]
set low = $argv[1]set high = $argv[2]set sum = 0set current = $lowwhile ( $current <= $high) @ sum += $current @ current++endecho The sum of the numbers from $low to $high is $sum.
Searching the File Tree: Find Command
General form
find filename…expression…
find ~ -name \*.awk –print
Searches the subtree rooted at home directory visiting each file and printing each file that ends in .awk
Some important primary expressions
• -atime n
• -name filename
• -exec cmd (end of command must be punctuated by a space then \;)
• -newer file
(see pages 149-151 of text for more details)
The different shells
Name # of internal Size of Complexity
of shell commands man pages
sh 32 44,000 1.0
csh 52 77,000 1.73
bash 50 127,000 2.86
zsh 73 133,000 3.00
ksh 43 141,000 3.18
tcsh 56 199,800 4.99
The if Statement – Bourne Shell
if [ condition ]
then
commands
else
commands
fi
Test condition operators – Bourne shell
String = stringString != stringValue –eq valueValue –ne valueValue –gt valueValue –ge valueValue –lt valueValue –le value
Referencing arguments – Bourne shell
$0, $1, $2, … (same as csh)
$* (list of all the variable)
$# (number of variables)
Bourne shell script#!/bin/sh
# lookup a person's phone number in the phone book
if [ $# -ne 1 ]then echo "\nusage:$0 name\n"else grep "$1" phone_bookfi
The while Statement – Bourne Shell
while [ condition ]
do
commands
done
Infinite Loop
while true
while :
The for Statement – Bourne Shell
for variable in list
do
commands
done
#!/bin/sh
for index in 1 2 3 4 5
do
echo $index
done
Clean - Bourne Shell
http://www.ececs.uc.edu/~berman/620/cleanbourne
File Types
1. Ordinary file – contains text, programs, or other data
2. Directory – contains names and addresses of other files
3. Special file – represents an I/O device4. Link – pointer to another file5. Socket – used for interprocess
communication