[SOLVED] Writing a simple bash script to take notes

Ghost-Order · 04-10-2020, 12:55 PM

Hello, I'm recently following an online course about Bash scripting, in the video the teacher write a simple script to takes notes and save those in a txt file, the script file name is "tn" and is as follows:

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt

Next, he add a line of code to show a confirmation message to the user with the note:

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo Note saved: $*

So when he runs the script "tn this is a new note" the terminal displays the message "Note saved: this is a new note" instead of showing nothing as before. However, when I write the script myself and then run it on the terminal, it doesn't display the confirmation message I just implemented in the script(although it write my note correctly in the txt file), in fact it seems that the second line of the script as a whole is not executed because I tried replacing echo Note saved: $* with echo $(date): $* >> ~/notes2.txt so when I run the script it should create a notes2.txt file and then write my note into it but it doesn't.

I checked again and again and my script is exactly the same as the video, sorry if this is a utterly simple question, but I really don't understand why it isn't working, what could be the problem?

pan64 · 04-10-2020, 12:57 PM

would be nice to post your script.

Ghost-Order · 04-10-2020, 01:00 PM

Quote:

Originally Posted by pan64

would be nice to post your script.

I didn't because is the same as the one that is in the video which I include in the initial post.

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo Note saved: $*

rtmistler · 04-10-2020, 01:01 PM

If you type into the command line exactly this:

Code:

echo $(date): abc

It should echo the date and also the string 'abc'.

Does this not work correctly on your system?

Can you also provide the output you see when you type:

Code:

$ echo $SHELL

pan64 · 04-10-2020, 01:03 PM

Quote:

Originally Posted by Ghost-Order

I didn't because is the same as the one that is in the video which I include in the initial post.

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo Note saved: $*

No, it is not the same, you told you modified it to write into notes2.txt. The script you posted will never write into that file.

rtmistler · 04-10-2020, 01:04 PM

Note also that this part of the term:

Code:

>>  ~/notes.txt

causes the output to go to the notes.txt file.

If you also wish to see the result in stdout, meaning the terminal, there's a notation, but I'm unsure of it. I tried a few things and wasn't successful. This is related to Linux/Unix I/O redirection.

Ghost-Order · 04-10-2020, 01:36 PM

Quote:

Originally Posted by rtmistler

If you type into the command line exactly this:

Code:

echo $(date): abc

It should echo the date and also the string 'abc'.

Does this not work correctly on your system?

Can you also provide the output you see when you type:

Code:

$ echo $SHELL

That works correctly, the output is Fri 10 Apr 2020 01:23:42 PM -05: abc
The output of $ echo $SHELL is bash: $: command not found

Quote:

Originally Posted by pan64

No, it is not the same, you told you modified it to write into notes2.txt. The script you posted will never write into that file.

My apologize, that's because seeing that echo $(date): $* >> ~/notes2.txt didn't work I remove it and put back the echo Note saved: $* original line. Anyway I tried with:

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo Note saved: $*

and

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo $(date): $* >> ~/notes2.txt*

But in both cases only the first line is executed (and correctly), the second line is not.

Quote:

Originally Posted by rtmistler

Note also that this part of the term:

Code:

>>  ~/notes.txt

causes the output to go to the notes.txt file.

If you also wish to see the result in stdout, meaning the terminal, there's a notation, but I'm unsure of it. I tried a few things and wasn't successful. This is related to Linux/Unix I/O redirection.

I see, but in the video the script consist just in this

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo Note saved: $*

And just with that the terminal shows the message.

teckk · 04-10-2020, 02:20 PM

Code:

while :; do
    read -p "Write note then press enter: " note
    echo "$note" >> notes.txt
done

astrogeek · 04-10-2020, 03:07 PM

Quote:

Originally Posted by Ghost-Order

The output of $ echo $SHELL is bash: $: command not found

Do not add the leading $, that was simply the prompt character in the question.

Quote:

Originally Posted by Ghost-Order

Code:

#!/bin/bash
#Simple note-taking script

echo $(date): $* >> ~/notes.txt
echo $(date): $* >> ~/notes2.txt*

Although it probably would not break the script in this simplest case, you should not name the file with a trailing * character because it will result in unexpected behavior in other cases (for example with any existing filenames which fit the glob pattern).

I wonder if you have a confusion with the path as might result from working from a subdirectory and not seeing the file written to your home directory. Are you typing the code yourself or copy/pasting it into a file which might result in some character encoding problems.

That would not explain all that you have said, but I think you need to be a little more specific about the platform (Linux distro, other?), the execution environment and the exact code and commands being given.

Ghost-Order · 04-10-2020, 03:07 PM

I found the problem, I have 2 'tn' files in different locations, and I was modifying the wrong one. Now I just feel dumb lol. Anyways Thank you for the help.

michaelk · 04-10-2020, 03:07 PM

Code:

#!/bin/bash
#Simple note-taking script

echo "$(date): $*" >> ~/notes.txt
echo "Note saved: $*"

The script does work as posted. The author leaves out the quotes which prevent word splitting and globing. If there isn't an end of line character on the last line the script will not execute properly although I would of expected a run time error. Edit the file and move the cursor to the end of the line past the last double quote(") assuming you modify your script as above. Now press the enter key, save the file and try running it again.

How it works. The $* is an array of the command line arguments. When you run the script i.e
tn this is a new note

tn is the script that runs and this is a new note are command line arguments. Each argument is stored in a variable i.e $1=this $2=is and so on. $* expands all of the command line arguments into a string.

Code:

echo "$(date): $*" >> ~/notes.txt

This line writes the current date/time and command line arguments to the notes.txt file in your home directory

Code:

echo "Note saved: $*"

Outputs Note saved: this is a new note to the terminal.

Nevermind.

astrogeek · 04-10-2020, 03:10 PM

Quote:

Originally Posted by Ghost-Order

I found the problem, I have 2 'tn' files in different locations, and I was modifying the wrong one. Now I just feel dumb lol. Anyways Thank you for the help.

Ah! A kind of path confusion indeed! Thanks for the follow-up!

Ghost-Order · 04-10-2020, 03:21 PM

Quote:

Originally Posted by astrogeek

Ah! A kind of path confusion indeed! Thanks for the follow-up!

Yep, sorry for that.

Quote:

Originally Posted by michaelk

Code:

#!/bin/bash
#Simple note-taking script

echo "$(date): $*" >> ~/notes.txt
echo "Note saved: $*"

The script does work as posted. The author leaves out the quotes which prevent word splitting and globing. If there isn't an end of line character on the last line the script will not execute properly although I would of expected a run time error. Edit the file and move the cursor to the end of the line past the last double quote(") assuming you modify your script as above. Now press the enter key, save the file and try running it again.

How it works. The $* is an array of the command line arguments. When you run the script i.e
tn this is a new note

tn is the script that runs and this is a new note are command line arguments. Each argument is stored in a variable i.e $1=this $2=is and so on. $* expands all of the command line arguments into a string.

Code:

echo "$(date): $*" >> ~/notes.txt

This line writes the current date/time and command line arguments to the notes.txt file in your home directory

Code:

echo "Note saved: $*"

Outputs Note saved: this is a new note to the terminal.

Nevermind.

Thank you. Although as I said it was a location mistake from me, your explanation expand a little more my knowledge about this topic.

slackartist · 04-15-2020, 02:47 AM

fixed

Ghost-Order · 04-16-2020, 12:37 AM

Quote:

Originally Posted by slackartist

you could look at this too. i think i spent a couple years look into this and learning a lot in between but since you ask.

https://www.chiark.greenend.org.uk/~...m/aliases.html
dude youll need this if you want to compile notes correctly with the bash line variables

Hey, thank you for the info, I'll make sure to check it.