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gat3	05-27-2015 08:58 PM

To simplify my bash loop script

Hi folks.
I'd like to make a simplified loop script,like

#!/bin/sh
while true
do
command1;command2;command3
sleep $somevariabl
done

in that case I can only type like

#./loop.sh command1;command2;command3 somevariable.

how could I achieve this?

veerain

05-27-2015 09:09 PM

The code:

Code:

#!/bin/sh

while true; do

$1; $2; $3

sleep $4

done

You run the script like this:

Code:

./loop.sh "command1" "command2" "command3" "sleep_time"

And this script will loop indefinitely. So would need to terminate it with 'Ctrl-C' or using kill command.

Do read man page of bash. Also there are basic as well as advanced BASH guides available from TLDP.

gat3	05-27-2015 09:12 PM

thanks for your response.
But in the first place I don't know how many commands I would pass to the script.
So it looks not like a perfect form.

Quote:

Originally Posted by veerain (Post 5368475)

The code:

Code:

#!/bin/sh

while true; do

$1; $2; $3

sleep $4

done

You run the script like this:

Code:

./loop.sh "command1" "command2" "command3" "sleep_time"

Do read man page of bash. Also there are basicas well as advanced BASH guides available from TLDP.

veerain

05-27-2015 09:27 PM

So you can pass sleep_time as first parameter and the commands as next. And use a loop to execute the commands one by one.

gat3	05-27-2015 09:41 PM

Quote:

Originally Posted by veerain (Post 5368481)

So you can pass sleep_time as first parameter and the commands as next. And use a loop to execute the commands one by one.

can you explain more?
if I use a loop to execute the commands one by one,in what way I could pass those commands to the script?
since I don't know how many commands I would pass to.

veerain

05-27-2015 11:14 PM

You use a shell feature which gives user a count of how many positional parameters (arguments) were passed.

gat3	05-28-2015 03:05 AM

Quote:

Originally Posted by veerain (Post 5368511)

You use a shell feature which gives user a count of how many positional parameters (arguments) were passed.

many thanks

for var in "$@"
do
echo "$var"
done

gat3	05-28-2015 01:22 PM

I found some problem in those things.

Code:

> bash -x ./2.sh ls "ls |wc" "ls ~" "seq 1 3" "seq 1 3|wc"                          

+ for var in '"$@"'

+ ls

1.sh  2.sh  3.sh  4.sh  5.sh

+ for var in '"$@"'

+ ls '|wc'

ls: cannot access |wc: No such file or directory

+ for var in '"$@"'

+ ls '~'

ls: cannot access ~: No such file or directory

+ for var in '"$@"'

+ seq 1 3

1

2

3

+ for var in '"$@"'

+ seq 1 '3|wc'

seq: invalid floating point argument: 3|wc

Try `seq --help' for more information.



> cat 2.sh                                                                          

#!/bin/bash

for var in "$@"

do

$var

done

Can someone help me?

Habitual

05-28-2015 01:37 PM

for i in ls madness.

Code:

ls: cannot access ~: No such file or directory

and the use of "~"

ntubski

05-29-2015 08:03 AM

If you actually want to execute arbitrary shell commands (not just single programs), you should use eval:

Code:

for var in "$@"

do

    eval "$var"

done

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