Shell command or script to write simple output on screen under Linux and UNIX
Q. How do I simply write output from my shell script to on screen under BASH shell?
A. Most shell bash, ksh and others comes with echo and printf in built command. There is also printf (C like statement) command to format and display data on screen
echo command
All the parameters to the echo command are printed to the screen. For example:
echo "Hello World!"
You can add echo command to your shell script:
#!/bin/bash echo "Memory information" free -m echo "Disk information" df -h
printf command
You can also use printf command.
printf "Hello world\n"
Or use in a script as follows:
#!/bin/bash print "Memory information\n" free -m printf "Disk information\n" df -h
Where,
-
-n : It is a FORMAT controls the output as in C printf. \n is use to print new line.
More options
You can print a variable value with echo or printf command. First define a variable called DDAY:
DDAY="15-Aug-2007"
Now print a variable using echo command:
echo "$DDAY"
Output:
15-Aug-2007
Now print a variable using echo command:
printf "$DDAY\n"
Output:
15-Aug-2007
You can combine a shell variable with statements or command itself:
#!/bin/bash DDAY="15-aug-2007" echo "D-Day is on $DDAY" echo "Today is $(date)" echo "Linux version : $(uname -r)"
$(uname -r) or $(date) are examples of command substitution. It allows the output of a command to replace the command name. There are two forms:
$(command-name)
OR
`command-name`
Preserving white spacing (blank space)
Also note that when you want the output to preserve your spacing enclose output in double quote:
$ echo "This is a test and today is $(date)"
Do not use single quote for command substitution:
$ echo 'This is a test and today is $(date)'Output:
This is a test and today is $(date)
For more information read man page of printf and echo by typing following commands:
$ man echo
$ man printf
$ man bash
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Discussion on This FAQ
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February 11th, 2007 at 6:40 pm
Hi
I was trying for a boot script on fc3 inorder to
play an mp3 file on starting script time .But the GUI
get stucked after logged in . Could you help me.
August 10th, 2007 at 2:25 pm
How can a simple shell interface respont to the following commands
1.Clr-Clear Screen
2.quit-quits the screen
3.echo prints the comments on the screen followed by a new line
4.copy file1.txt,file2.txt.create a copy of file1.txt with a new name file2.txt