Difference between revisions of "OPS435 Lecture 4 - Bash"
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* Program control: | * Program control: | ||
** if | ** if | ||
| − | ** test | + | ** test, [ |
| − | ** | + | ** [[ |
| − | ** | + | * Parameter expansion examples |
| − | * read command | + | ** echo $1 |
| + | ** echo ${11} | ||
| + | * Input from the user | ||
| + | ** read command | ||
| + | |||
| + | == In-class examples == | ||
| + | |||
| + | runme.sh: | ||
| + | <source lang="bash"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | echo "First parameter was $1" | ||
| + | echo Second: $2 | ||
| + | echo 'Third parameter: ' $3 | ||
| + | echo "Fourth parameter was $4" | ||
| + | </source> | ||
| + | |||
| + | divide.sh: | ||
| + | <source lang="bash"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | if [[ $# -lt 1 ]] | ||
| + | then | ||
| + | echo "Not enough parameters" | ||
| + | exit | ||
| + | fi | ||
| + | |||
| + | echo $(( $1 / 2 )) | ||
| + | </source> | ||
| + | |||
| + | stringtest.sh: | ||
| + | <source lang="bash"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | COMPARETO=hello | ||
| + | COMPARETO="hello" | ||
| + | COMPARETO='hello' | ||
| + | |||
| + | if [ x$1 = x$COMPARETO ] | ||
| + | then | ||
| + | echo "You guessed the string" | ||
| + | else | ||
| + | echo "Guess again" | ||
| + | fi | ||
| + | </source> | ||
| + | |||
| + | testcommand.sh: | ||
| + | <source lang="bash"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | if ls /etc/linuxmint > /dev/null 2> /dev/null | ||
| + | then | ||
| + | echo "Correct distribution" | ||
| + | else | ||
| + | echo "Please run this script on linux mint" | ||
| + | exit | ||
| + | fi | ||
| + | |||
| + | FILETYPE=`file -b /etc/linuxmint` | ||
| + | #if [ "$FILETYPE" = "directory " ] | ||
| + | if test "$FILETYPE" = "directory " | ||
| + | then | ||
| + | echo "It's a directory as I expected" | ||
| + | else | ||
| + | echo "It's not a directory" | ||
| + | exit | ||
| + | fi | ||
| + | </source> | ||
| + | |||
| + | ask.sh: | ||
| + | <source lang="bash"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | echo "Script started" | ||
| + | echo "Please choose one of the following files: " | ||
| + | cd /var/log | ||
| + | ls syslog* | ||
| + | |||
| + | echo -n "Your choice: " | ||
| + | read CHOSENNAME | ||
| + | |||
| + | echo $CHOSENNAME | ||
| + | </source> | ||
Latest revision as of 12:40, 22 August 2017
- Writing a script
- Receiving parameters
- Return codes
- true and false commands
- Program control:
- if
- test, [
- [[
- Parameter expansion examples
- echo $1
- echo ${11}
- Input from the user
- read command
In-class examples
runme.sh:
#!/bin/bash
echo "First parameter was $1"
echo Second: $2
echo 'Third parameter: ' $3
echo "Fourth parameter was $4"divide.sh:
#!/bin/bash
if [[ $# -lt 1 ]]
then
echo "Not enough parameters"
exit
fi
echo $(( $1 / 2 ))stringtest.sh:
#!/bin/bash
COMPARETO=hello
COMPARETO="hello"
COMPARETO='hello'
if [ x$1 = x$COMPARETO ]
then
echo "You guessed the string"
else
echo "Guess again"
fitestcommand.sh:
#!/bin/bash
if ls /etc/linuxmint > /dev/null 2> /dev/null
then
echo "Correct distribution"
else
echo "Please run this script on linux mint"
exit
fi
FILETYPE=`file -b /etc/linuxmint`
#if [ "$FILETYPE" = "directory " ]
if test "$FILETYPE" = "directory "
then
echo "It's a directory as I expected"
else
echo "It's not a directory"
exit
fiask.sh:
#!/bin/bash
echo "Script started"
echo "Please choose one of the following files: "
cd /var/log
ls syslog*
echo -n "Your choice: "
read CHOSENNAME
echo $CHOSENNAME