/dev/chat

8:56 AM

i dont get why this doesnt work
```
while $LINE_CONTENT -ne $(head -1 to_be_installed.txt)
do
LINE_CONTENT=$(tail -$N to_be_installed.txt)
apt-get install $LINE_CONTENT
done

```

terdon

9:06 AM

@AdamL because the syntax is completely wrong? You might want to look at some basic shell scripting tutorials. You can't use -ne as a command, it is only relevant within a test ([ or [[ or test). Your code is trying to run the contents of $LINE_CONTENT as a command, passing ` -ne $(head -1 to_be_installed.txt)` to it as arguments.

Since $LINE_CONTENT doesn't contain a valid command, you get an error.

And the logic doesn't make much sense anyway, your N will never change so you will be running an infinite loop

Presumably, you wanted something like this:

n=1
line_content=$(tac to_be_installed.txt | head -n $n | tail -n1)

while [ "$line_content" -ne "$(head -n1 to_be_installed.txt)" ]
do
  line_content=$(tac to_be_installed.txt | head -n "$n" | tail -n1)
  apt-get install "$line_content"
  ((n++))
done

Adam L

```
N=0
#!/bin/sh
LAST_LINE=$(head -$1 to_be_installed.txt)
LINE_CONTENT=$NULL
while [ "LINE_CONTENT" != "$LAST_LINE" ]
do
N=$(N+1)
LINE_CONTENT=$(tail -$N to_be_installed.txt)
apt-get install $LINE_CONTENT
done
```

ok yeah sorry just woke up probably need to eat breakfast dinner

fra-san

9:22 AM

@AdamL Code-fence formatting doesn't work in chat. You need to paste your code without the backticks and use the "fixed font" button that appears on the right of the composing box.

Adam L

ok thank you

fra-san

@terdon Won't it complain because -ne expects integer operands?

Adam L

@terdon I get an error line 6: [: zlib1g: integer expression expected

ah ok

fra-san

@AdamL Yeah, see my previous comment. String inequality requires !=.

@AdamL Also, the shebang line (#!/bin/sh) needs to be the first one of the file.

terdon

@fra-san lol, of course it will, but just not if you're an idiot and use seq 10 > file as a file to test it on :)

Like I did.

here you go:

n=1
line_content=$(tac to_be_installed.txt | head -n $n | tail -n1)

while [ "$line_content" != "$(head -n1 to_be_installed.txt)" ]
do
  line_content=$(tac to_be_installed.txt | head -n "$n" | tail -n1)
  echo apt-get install "$line_content"
  ((n++))
done

Adam L

9:32 AM

I need one of those drinking duck things to press the Y button for me now like in the Simpsons when they let him work from home\

fra-san

@AdamL Search the manual of your commands for -y or yes. They often have a built-in "always-say-yes" duck.

@AdamL And in general: N=$(N+1) should be N=$((N+1)) -- see "command substitution" VS "arithmetic expansion"; double-quote your expansions (e.g. apt-get install "$LINE_CONTENT") unless you know you need word splitting and filename generation. shellcheck.net may help you spot issues in your scripts.

Adam L

ok thanks

terdon

10:02 AM

Also, avoid using CAPITALS for variable names, that's bad practice since env vars are in allcaps and if you do the same for your vars, you can have variable collision.

And yes, apt-get has a -y option:

-y, --yes, --assume-yes
Automatic yes to prompts. Assume "yes" as answer to all prompts and run non-interactively. If an undesirable situation, such as changing a held package or removing an essential package, occurs then apt-get will abort.

fra-san

@terdon Testing code is much harder than writing it, I suspect :-)

Transcript for