${filename%.*} Extracting the filename by stripping off the file extension

$ FN="filename.jsp
$ echo ${FN%.*}
filename

${filename##*.} Extracting the file extension of filename

$ FN="FileName.jsp"
$ echo ${FN#*.}
jsp

${#string} Getting the length of a string

$ WORD=Supercalifragilisticexpialidocious
$ echo $WORD
Supercalifragilisticexpialidocious
$ echo ${#WORD}
34

${var=default} If var is not set, set it to default

$ echo $username
null
$ echo ${username=`whoami`}
islandjoe
$ echo $username
islandjoe

${var-default} If var is not set, use a default

$ echo $username
null
$ echo ${username-`whoami`}
islandjoe
echo $username
null

If arg is empty print the current working directory instead

Our Nautilus script named "Xyz":

Demo

If we select a file:



It returns the name of the file:



And if we don't select a file:



It returns the name of its current working directory:

How to get the parent directory of a folder

$ dirname `pwd`

In shell script:

VAR=${dirname `pwd`}

Special characters and operators

$var -Variable



${var} -Same as $var



${var-default} -If $var is not set, use the string "Morjens"



${var=default} -If $var is not set, set it to default and use that value.





${var+instead} - If $var is set, use instead. Otherwise empty string.




${var?message} -If $var is not set, print message. If $var is set, use its value.