I've started reading this: http://www.tldp.org/LDP/abs/abs-guide.pdf

An exercise says that I should write a script that shows the date, uptime and lists all logged-in users and which creates a log with this information.

So I don't know how to write this script, except by writing the commands twice.

This is what I did, but when the file is written in under /var/log, only the input of the last command (uptime) is written in the file.

Any suggestions?

Your "&&"s start a new command and so the pipe to tee only receives the output of the last echo. Use one echo or multiple tees.

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The "echo" parts are kind of unnecessary. You can run the programs plain without the backticks, but group them inside a set of parenthesis and then pipe the output of the parenthesis to "tee"

Later, if you do need command substitution you can use $( ... ) instead of backticks. It will be a bit easier to read and can even be nested.

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Hi,

What you need to learn is I/O redirection.

The && only waits for the preceding command to finish and if the return value is 0, then proceeds to the next command.

The pipe ( | ) is a form of I/O redirection.

The above example command actually takes the output obtained from program1 and pipes it into program2. Basically, output of program1 becomes input for program2.

For this one, the output of program1 will be redirected to the regular file textfile.log. In other words, if program1 normally outputs messages on the standard output (your terminal screen), then this output will now be placed in the regular file after the ">".

The "| tee" in your command replaces the ">", and the && only look at the return values from the echo's. So, you need to use a single echo or multiple echo's on different lines and each with their respective tee's or >

Isn't that supposed to be between brackets? It doesn't work with { } But it does with brackets. I suppose I could also simply redirect it to /var/log/whatever and then simply cat that /var/log/whatever. Thought of it afterwards.

But I guess I'm going back to turbocapitalist's answer. So that's quite logical, indeed.

But how can I append the output using tee? So displaying stdout, but also appending it to a certain file?

You can append with -a, according to the manual page for "tee". There's also "tee --help" but that gives about the same information. If you leave off the -a it will overwrite the file.

If you use redirects, you can append with >>

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Ok, I simply needed to add -a to tee. Thank you all for your helpful answers!

Sorry, I saw your post afterwards

It's just mising a semicolon:

Weird that between brackets it should work without the last semicolon, whereas with curly brackets it needs the semicolon.