bash, 1987, ang. Bourne

Bash
✦ Steve Bourne (sh, 1977), Brian Fox (bash, 1987, ang.
Bourne-Again Shell), Chet Ramey (1990)
✦ http://steve-parker.org/sh/sh.shtml
✦ http://www.ooblick.com/text/sh/
✦ env | grep SHELL
✦ $ bash
✦ $ echo Hello World
Hello World
$
✦ #!/bin/sh
# This is a comment!
echo Hello World # This is a comment, too!
✦ $ chmod 755 first.sh
$ ./first.sh
Hello World
$
Bash (c.d.)
✦ Zmienne
✦ $ env
✦ #!/bin/sh
MY_MESSAGE="Hello World"
echo $MY_MESSAGE
✦ $ chmod 755 var.sh
$ ./var.sh
Hello World
$
✦ $ MY_MESSAGE="Hello World"
$ echo $MY_MESSAGE
$ env
$ export MY_MESSAGE
$ env
Bash (c.d.)
✦ Zmienne (c.d.)
✦ #!/bin/sh
echo "What is your name?"
read USER_NAME
echo "Hello $USER_NAME"
echo "I will create you a file called ${USER_NAME}_file"
touch "${USER_NAME}_file"
✦ $ ./user.sh
What is your name?
zssz
Hello zssz
I will create you a file called zssz_file
✦ $ ls –l zssz_file
-rw-r--r-- 1 zssz staff 0 paź 4 07:56 zssz_file
Bash (c.d.)
✦ Pętle
✦ #!/bin/sh
for i in 1 2 3 4 5
do
echo "Looping ... number $i"
done
✦ $ ./for.sh
Looping ... number 1
Looping ... number 2
Looping ... number 3
Looping ... number 4
Looping ... number 5
Bash (c.d.)
✦ Pętle (c.d.)
✦ #!/bin/sh
INPUT_STRING=hello
while [ "$INPUT_STRING" != "bye" ]
do
echo "Please type something in (bye to quit)"
read INPUT_STRING
echo "You typed: $INPUT_STRING"
done
✦ $ ./while.sh
Please type something in (bye to quit)
zssz
You typed: zssz
Please type something in (bye to quit)
bye
You typed: bye
$
Bash (c.d.)
✦ Case
✦ $ ./talk.sh
Please talk to me ...
hello
Hello yourself!
zssz
Sorry, I don't understand
bye
See you again!
That's all folks!
#!/bin/sh
echo "Please talk to me ..."
while :
do
read INPUT_STRING
case $INPUT_STRING in
hello)
echo "Hello yourself!"
;;
bye)
echo "See you again!"
break
;;
*)
echo "Sorry, I don't understand"
;;
esac
done
echo "That's all folks!"
Bash (c.d.)
Command
&
&&
||
^
$
=
!
$$
$!
$?
$0
$1
$9
$@
$*
Description
background
Logical AND
Logical OR
Start of line
End of line
String equality (cf. -eq)
Logical NOT
PID of current shell
PID of last background
exit status
Name of command
Name of first parameter
ninth parameter
All parameters
not preserving quoting
Example
ls &
if [ "$foo" -ge "0" ] && [ "$foo" -le "9"]
if [ "$foo" -lt "0" ] || [ "$foo" -gt "9" ] (!bash)
grep "^foo"
grep "foo$ "
if [ "$foo" = "bar" ]
if [ "$foo" != "bar" ]
echo "my PID = $$"
ls & echo "PID of ls = $!"
ls ; echo "ls returned code $?"
echo "I am $0"
echo "My first argument is $1"
echo "My ninth argument is $9"
echo "My arguments are $@"
echo "My arguments are $*"
Bash (c.d.)
Command
-eq
-ne
-lt
-le
-gt
-ge
-z
-n
-nt
-d
-f
-r
-w
-x
parenthesis: ( ... )
Description
Example
Numeric Equality
if [ "$foo" -eq "9" ]
Numeric Inquality
if [ "$foo" -ne "9" ]
Less Than
if [ "$foo" -lt "9" ]
Less Than or Equal
if [ "$foo" -le "9" ]
Greater Than
if [ "$foo" -gt "9" ]
Greater Than or Equal
if [ "$foo" -ge "9" ]
String is zero length
if [ -z "$foo" ]
String is not zero length if [ -n "$foo" ]
Newer Than
if [ "$file1" -nt "$file2" ]
Is a Directory
if [ -d /bin ]
Is a File
if [ -f /bin/ls ]
Is a readable file
if [ -r /bin/ls ]
Is a writable file
if [ -w /bin/ls ]
Is an executable file
if [ -x /bin/ls ]
Function definition
function myfunc() { echo hello }
Bash (c.d.)
✦ Potoki
✦ ps -ef | grep –ef named
✦ Przekierowanie
✦ stdin (0); stdout (1); stderr (2)
✦ stdout: ls – l >plik1; ls –l >>plik1
✦ stdin: cat <plik1
✦ <&digit – użyj digit jako stdin
✦ >&digit – użyj digit jako stdout
✦ ps 2>&1 >myps
Bash (c.d.)
✦ Test (/bin/[)
✦ operacje logiczne
✦ ! – negacja, -a - koniunkcja,
-o - alternatywa
✦ opcje
✦ -r - można czytać; -w - można
pisać; -x – można wykonywać;
-d – plik jest katalogiem,
–f - plik jest zwykłym plikiem
✦ $ touch abc
$ chmod 644 abc
$ ./file.sh
Podaj nazwe pliku!
$ ./file.sh abc
Mozna pisac i czytac abc
$ chmod 444 abc
$./file.sh abc
Nie mozna pisac lub czytac abc
#!/bin/sh
if test $1
then if test -w $1 -a -r $1
then echo "Mozna pisac i czytac $1"
else
echo "Nie mozna pisac lub czytac $1"
fi
else echo "Podaj nazwe pliku!"
fi
Bash (c.d.)
✦ Debugging
✦ opcja –n tylko czytanie skryptu
✦ opcja –x wypisanie polecenia na stderr i wykonanie
#!/bin/sh
ps –ef > /dev/null
set -x
ps –ef > dev/null
set +x
ps –ef > /dev/null
✦ $ ./debug.sh
+ ps –ef
./debug.sh: line 4: dev/null: Nie ma takiego pliku ani katalogu
+ set +x