Shell Scripting - Revision history

Bacchas: /* Using Wildcards */

2022-06-30T14:47:52Z

Using Wildcards

← Older revision		Revision as of 14:47, 30 June 2022
Line 161:		Line 161:

	#!/bin/bash		#!/bin/bash
	cd /var/www/bash		cd /var/www/bash
	# there's a space after the "if", space afer ! then a space after "[", space before "]"		# there's a space after the "if", space afer ! then a space after "[", space before "]"
	if [ ! -d /var/www/bash/text/ ]		if [ ! -d /var/www/bash/text/ ]

Bacchas: /* Using Wildcards */

2022-06-30T14:47:19Z

Using Wildcards

← Older revision		Revision as of 14:47, 30 June 2022
Line 132:		Line 132:
	===Using Wildcards ===		===Using Wildcards ===

	<~~code~~>		<pre>
	* -matches zero or more characters		* -matches zero or more characters
	*.txt		*.txt
Line 158:		Line 158:
	[[:upper:]]		[[:upper:]]
	[[:space:]]		[[:space:]]
	</~~code~~>		</pre>

	#!/bin/bash		#!/bin/bash
Line 172:		Line 172:
	cp $FILE /var/www/bash/text		cp $FILE /var/www/bash/text
	done		done

	===Case Statements===		===Case Statements===

Bacchas: /* Creating a Function */

2022-06-30T14:46:42Z

Creating a Function

← Older revision		Revision as of 14:46, 30 June 2022
Line 89:		Line 89:

	=== Creating a Function ===		=== Creating a Function ===
	~~<pre>~~
	function function-name() {# code goes here}		'''function function-name() <code>{# code goes here}</code>'''
	Calling a Function
	function hello() {		===Calling a Function===

			function hello() {
	echo "hello:		echo "hello:
	}		}
	hello (you don't need the () just call the name of the function)
			'''hello (you don't need the () just call the name of the function)'''

	** Positional Parameters and passing info to a ~~funciton~~		===Positional Parameters and passing info to a function===

			#!/bin/bash
	#!/bin/bash
	function hello(){		function hello(){
	echo "hello $1"		echo "hello $1"
Line 106:		Line 108:
	}		}

	~~hello robert # robert is passed to the function hello~~
	~~#output is hello Robert~~
	** Outputting miltple calls to a function

			'''hello robert # robert is passed to the function hello'''

			#output is hello Robert

			=== Outputting multiple calls to a function===

	#!/bin/~~bahs~~
	~~funciton~~ hello() {		#!/bin/bash
			function hello() {
	for NAME in $@		for NAME in $@
	do		do
Line 119:		Line 124:
	}		}

	hello robert bob dan		hello robert bob dan

			'''Output'''

			hello robert bob dan

	~~Output~~		===Using Wildcards ===
	~~hello robert bob dan~~
	~~Using Wildcards~~		<code>
	* -matches zero or more characters		* -matches zero or more characters
	*.txt		*.txt
Line 149:		Line 158:
	[[:upper:]]		[[:upper:]]
	[[:space:]]		[[:space:]]
			</code>

	#!/bin/bash		#!/bin/bash
	cd /var/www/bash		cd /var/www/bash
	# there's a space after the "if", space afer ! then a space after "[", space before "]"		# there's a space after the "if", space afer ! then a space after "[", space before "]"
	if [ ! -d /var/www/bash/text/ ]		if [ ! -d /var/www/bash/text/ ]
	then		then
	mkdir /var/www/bash/text		mkdir /var/www/bash/text
	fi		fi
	for FILE in *.txt		for FILE in *.txt
	do		do
	echo "Copying $FILE"		echo "Copying $FILE"
	cp $FILE /var/www/bash/text		cp $FILE /var/www/bash/text
	done		done
	Case Statements		===Case Statements===
	~~</pre>~~


	=== Simple Backup bash shell script ===		=== Simple Backup bash shell script ===

Bacchas: /* = &bull, $? contains the return code of the previously executed command */

2022-06-30T14:07:46Z

= &bull, $? contains the return code of the previously executed command

← Older revision		Revision as of 14:07, 30 June 2022
Line 11:		Line 11:
	===Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status===		===Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status===

	===<code> &bull, $? </code> contains the return code of the previously executed command==		=== <code> &bull, $? </code> contains the return code of the previously executed command===

	ls /not/here		ls /not/here

Bacchas: /* =&bull, $? contains the return code of the previously executed command */

2022-06-30T14:07:12Z

=&bull, $? contains the return code of the previously executed command

← Older revision		Revision as of 14:07, 30 June 2022
Line 11:		Line 11:
	===Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status===		===Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status===

	===<code>&bull, $? </code> contains the return code of the previously executed command==		===<code> &bull, $? </code> contains the return code of the previously executed command==

	ls /not/here		ls /not/here

Bacchas: /* Shell Scripting */

2022-06-30T14:06:39Z

Shell Scripting

← Older revision		Revision as of 14:06, 30 June 2022
Line 1:		Line 1:
	== Shell Scripting ==		== Shell Scripting ==

	~~<pre>~~
	~~• Scripts must be chmod 755 so they can execute~~

	~~• #!/bin/bash~~ (add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs)		===Scripts must be chmod 755 so they can execute===

			'''(add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs)'''
			#!/bin/bash

	• Positional Parameters: $0 ... $9 $@ to access all 0-9 // like in a loop		=== Positional Parameters:<code> $0 ... $9</code> $@ to access all 0-9 // like in a loop===

	• Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status		===Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status===

	&bull, $? contains the return code of the previously executed command		===<code>&bull, $? </code> contains the return code of the previously executed command==

	ls /not/here		ls /not/here
	echo "$?"		echo "$?"
	Another Code example		'''Another Code example'''

			HOST="google.com"
	HOST="google.com"		ping -c 1 $HOST # -c 1 means it will send 1 ping
	ping -c 1 $HOST # -c 1 means it will send 1 ping		if["$?" -eg "0"]
	if["$?" -eg "0"]		then
	then		echo "$HOST reachable"
	echo "$HOST reachable"
	else		else
	"$HOST unreachable"		"$HOST unreachable"
	fi		fi
	~~&& and \|\|~~
	~~-the second statement only executes if the first one was successfull~~
	~~mkdir /tmp/bak && cp test.txt /tmp/bak/~~
	~~-the second statement will execute only if the first one fails~~
	~~cp test.txt /tmp/bak/ \|\| cp test.txt /tmp~~
	~~• chain multiple commands together using a ; (semicolon) cp test.txt /tmp/ ; cp test.txt /bak~~

	</~~pre>~~		&& and \|\|

			'''the second statement only executes if the first one was successful'''
			mkdir /tmp/bak && cp test.txt /tmp/bak/

			'''the second statement will execute only if the first one fails'''
			cp test.txt /tmp/bak/ \|\| cp test.txt /tmp
			===chain multiple commands together using a ; (semicolon) ===
			cp test.txt /tmp/ ; cp test.txt /bak


	===File Operators (test)===		===File Operators (test)===
Line 184:		Line 187:

	----		----

	==[[#Shell Scripting\|Back To Top]]-[[Main_Page\| Home]] - [[Ubuntu_Tips\|Category]]==		==[[#Shell Scripting\|Back To Top]]-[[Main_Page\| Home]] - [[Ubuntu_Tips\|Category]]==

Bacchas: Created page with "== Shell Scripting ==

 • Scripts must be chmod 755 so they can execute  • #!/bin/bash (add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs)  • Positional Parameters: $0 ... $9 $@ to access all 0-9 // like in a loop  • Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status  &bull, $? contain..."

2022-05-29T19:06:15Z

Created page with "== Shell Scripting == <pre> • Scripts must be chmod 755 so they can execute • #!/bin/bash (add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs) • Positional Parameters: $0 ... $9 $@ to access all 0-9 // like in a loop • Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status &bull, $? contain..."

New page

== Shell Scripting ==

<pre>
• Scripts must be chmod 755 so they can execute

• #!/bin/bash (add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs)

• Positional Parameters: $0 ... $9 $@ to access all 0-9 // like in a loop

• Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status

&bull, $? contains the return code of the previously executed command

ls /not/here
echo "$?"
Another Code example

HOST="google.com"
ping -c 1 $HOST # -c 1 means it will send 1 ping
if["$?" -eg "0"]
then
echo "$HOST reachable"
else
"$HOST unreachable"
fi
&& and ||
-the second statement only executes if the first one was successfull
mkdir /tmp/bak && cp test.txt /tmp/bak/
-the second statement will execute only if the first one fails
cp test.txt /tmp/bak/ || cp test.txt /tmp
• chain multiple commands together using a ; (semicolon) cp test.txt /tmp/ ; cp test.txt /bak

</pre>

===File Operators (test)===
<pre>
-d FILE -true if is a directory
-e FILE True if file exists
-f FILE True if file exist and is a regular file
-r FILE True if file is readable by you
-s FILE True if file exists and is not empty
-w FILE True if file is writable by you
-x FILE True if file is executable by you
-z FILE True if string is empty
-n FILE True if string is not empty
String1=String2 true if strings are equal
String1 != string2 True if the strings are not equal
arg1 -eq arg2 equal
arg1 -ne arg2 not equal
arg1 -lt arg2 less than
arg1 -le arg2 less than or equal to
arg1 -gt arg2 greater than
arg1 -ge arg2 greater than or equal to
read -p "Prompt to dispaly" VarableName accepting user input
</pre>
=== for loop to rename all jpg files with the date ===
<pre>
#!/bin/bash
PICTURES=$(ls *.jpg)
DATE=$ (date +%F)

for PICTURES IN $PICTURES
do
echo "Renaming ${PICTURE} to ${DATE} - ${PICTURE}"
mv $[PICTUE} ${DATE}-${PICTURE}
done

// Output
renaming bear.jpg to 2015-03-06-bear.jpg
</pre>

=== Adding exit commands to scripts ===

<pre>
#!/bin/bash
HOST="google.com"
ping -c 1 $HOST
IF [ "$?" -ne"0" ]
then
echo "$HOST unrechale"
exit 1
fi
exit 0
</pre>

=== Creating a Function ===
<pre>
function function-name() {# code goes here}
Calling a Function
function hello() {
echo "hello:
}
hello (you don't need the () just call the name of the function)

** Positional Parameters and passing info to a funciton

#!/bin/bash
function hello(){
echo "hello $1"

}

hello robert # robert is passed to the function hello
#output is hello Robert
** Outputting miltple calls to a function

#!/bin/bahs
funciton hello() {
for NAME in $@
do
echo "Hello $NAME"
done
}

hello robert bob dan

Output
hello robert bob dan
Using Wildcards
* -matches zero or more characters
*.txt
a*
a*.txt
? - matches exactly one character
?.txt
a?
a?.txt
[] character class - matches any of the characters included between the brackets. Matches exactly one character.
[aeiou]* exampld: ls -la [abge]*
ca[nt] matches:(it will match either the n or the t)
can, cat, candy, catch
[!] Matches any characters NOT included between the brackets. Matches exactly one character.
[!aeiou]* would match below bacause it does not start with any of those letters
baseball, cricket
Select a range
[a-g]* matches files that start with a,b,c,d,e,f,g
[3-6]* matches all files start with 3,4,5,6
Using predefined Character Classes
[[:alpha:]]
[[:alnum:]]
[[:digit:]]
[[:lower:]]
[[:upper:]]
[[:space:]]

#!/bin/bash
cd /var/www/bash
# there's a space after the "if", space afer ! then a space after "[", space before "]"
if [ ! -d /var/www/bash/text/ ]
then
mkdir /var/www/bash/text
fi
for FILE in *.txt
do
echo "Copying $FILE"
cp $FILE /var/www/bash/text
done
Case Statements
</pre>

=== Simple Backup bash shell script ===
<pre>
#!/bin/bash
tar -czf myhome_directory.tar.gz /home/linuxconfig

Your backup script and variables:
#!/bin/bash
OF=myhome_directory_$(date +%Y%m%d).tar.gz
tar -czf $OF /home/linuxconfig

We can use while loop to check if file does not exists. This script will sleep until file does exists. Note bash negator "!" which negates the -e option.
#!/bin/bash

while [ ! -e myfile ]; do
# Sleep until file does exists/is created
sleep 1
done

</pre>

----
==[[#Shell Scripting|Back To Top]]-[[Main_Page| Home]] - [[Ubuntu_Tips|Category]]==