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New page: = Running a Bash Script = Enter this script into the file "script1" in the current directory (it's a good idea to create a directory for this lab): #!/bin/bash SECRET=$(( RANDOM % 100 ...
= Running a Bash Script =
Enter this script into the file "script1" in the current directory (it's a good idea to create a directory for this lab):
#!/bin/bash
SECRET=$(( RANDOM % 100 + 1))
INPUT=0
GUESSES=0
echo "Guess the secret: a number between 1 and 100."
while [ "$INPUT" -ne "$SECRET" ]
do
echo -n "Your guess: "
read INPUT
if [ "$INPUT" -eq "$SECRET" ]
then
echo "Correct!"
elif [ "$INPUT" -gt "$SECRET" ]
then
echo "Too high."
else
echo "Too low."
fi
((GUESSES++))
done
echo "You took $GUESSES tries."
Make the script executable:
chmod u+x script1
Try running the script:
script1
If that doesn't work, specify the directory:
./script1
Or add the current directory to the path:
PATH="$PATH:."
Read through the script and make sure you understand what it does. Use [[BASH]] wiki page and the bash manpage for reference.
= Reading Bash Scripts =
Guess what each of these scripts does, and then test your assumption.
#!/bin/bash
if false
then
echo "1"
elif true
then
echo "2"
else
echo "3"
fi
#!/bin/bash
for ((x=0; x<5; x++))
do
echo $x
done
#!/bin/bash
for NAME in /etc/*
do
if [ -r "$NAME" -a -f "$NAME" ]
then
wc -c "$NAME"
fi
done
= Writing BASH Scripts =
Write scripts to do three of the following tasks:
* Loop through the files in your home directory, and for each readable file, ask whether the file should be printed, mailed to you, or ignored (P/M/I) and then take the appropriate action.
* Display the longest and shortest usernames on the system (usernames are in the first field in /etc/passwd).
* Count the number of users with user IDs between 500 and 10000 on the system (user IDs are the third field in /etc/passwd).
* Display the names of any filesystems which have less than 10% free space available (see the <code>df</code> command for this information).
* Ask the user for an e-mail address, then send the output of the <code>dmesg</code> command to that address.
* Count the number of files in the user's home directory which are not readable.
* For each directory in the $PATH, display the number of executable files in that directory.
Enter this script into the file "script1" in the current directory (it's a good idea to create a directory for this lab):
#!/bin/bash
SECRET=$(( RANDOM % 100 + 1))
INPUT=0
GUESSES=0
echo "Guess the secret: a number between 1 and 100."
while [ "$INPUT" -ne "$SECRET" ]
do
echo -n "Your guess: "
read INPUT
if [ "$INPUT" -eq "$SECRET" ]
then
echo "Correct!"
elif [ "$INPUT" -gt "$SECRET" ]
then
echo "Too high."
else
echo "Too low."
fi
((GUESSES++))
done
echo "You took $GUESSES tries."
Make the script executable:
chmod u+x script1
Try running the script:
script1
If that doesn't work, specify the directory:
./script1
Or add the current directory to the path:
PATH="$PATH:."
Read through the script and make sure you understand what it does. Use [[BASH]] wiki page and the bash manpage for reference.
= Reading Bash Scripts =
Guess what each of these scripts does, and then test your assumption.
#!/bin/bash
if false
then
echo "1"
elif true
then
echo "2"
else
echo "3"
fi
#!/bin/bash
for ((x=0; x<5; x++))
do
echo $x
done
#!/bin/bash
for NAME in /etc/*
do
if [ -r "$NAME" -a -f "$NAME" ]
then
wc -c "$NAME"
fi
done
= Writing BASH Scripts =
Write scripts to do three of the following tasks:
* Loop through the files in your home directory, and for each readable file, ask whether the file should be printed, mailed to you, or ignored (P/M/I) and then take the appropriate action.
* Display the longest and shortest usernames on the system (usernames are in the first field in /etc/passwd).
* Count the number of users with user IDs between 500 and 10000 on the system (user IDs are the third field in /etc/passwd).
* Display the names of any filesystems which have less than 10% free space available (see the <code>df</code> command for this information).
* Ask the user for an e-mail address, then send the output of the <code>dmesg</code> command to that address.
* Count the number of files in the user's home directory which are not readable.
* For each directory in the $PATH, display the number of executable files in that directory.
