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Re: [PROGRAMMERING] En 'for' lykke i konsolen



Jan Trøjgaard <sslug@sslug> writes:

>>> > Lykken(erne) jeg skriver ser sådan ud:
>>> > sslug@sslug:~$ for freq in $((seq 200 20 2000)): beep -f $freq: done
>>> 
>>> bash her.
>> 
>> men det virker sådan her:
>> for freq in `seq 200 20 200`; do beep -f $freq; done
>
> Den giver kune ét beep på frekvensen 200 hertz! Men den siger noget.
> Jeg har også lige prøvet med et par andre variationer:
> sslug@sslug:~$ for freq in $((`seq 200 20 200`)); do beep -f $freq; done
> sslug@sslug:~$ for freq in $((seq 200 20 200)); do beep -f $freq; done
> bash: seq 200 20 200: syntax error in expression (error token is "200 20
> 200")
> sslug@sslug:~$ for freq in $((`seq 200 20 200`)); do beep -f $freq; done
> sslug@sslug:~$ for freq i in $((`seq 200 20 200`)); do beep -f $freq; done
> bash: syntax error near unexpected token `i'
> sslug@sslug:~$ for i freq in $((`seq 200 20 200`)); do beep -f $freq; done
> bash: syntax error near unexpected token `freq'

I bash betyder `command` og $(command) det samme, udfør command og sæt
uddata ind i den kommandolinje der er ved at blive bygget op.

For at lege lidt med det kan du prøve kommandoerne:
seq 200 20 200
seq 200 20 240
seq 200 20 2000
echo $(seq 200 20 240)
for freq in $(seq 200 20 200); do beep -f $freq; done
for freq in $(seq 200 20 240); do beep -f $freq; done
for freq in $(seq 200 20 2000); do beep -f $freq; done

-- 
Kim Hansen


 
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