Multiple commands in shell

ruby-talk
1

I'm trying to run multiple commands in the shell from ruby but I can't
seem to grasp how I keep the "state" from the previous shell command.

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

Not counting "ls /dir" that is :wink:

I've tried using:

system "cd /dir"
system "ls"

..but it doesn't work.

Thanks!

···

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Posted via http://www.ruby-forum.com/.

2

Gu stav wrote:

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

system "cd /dir; ls"
or:
Dir.chdir("/dir") do
  system "ls"
end
or even better:
puts Dir["/dir/*"]

Generally there's no way to have the state from one system command affect
another, but you can change the pwd with Dir.chdir and you can change
environment variables using ENV.

HTH,
Sebastian

···

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3

Gu stav schrieb:

I'm trying to run multiple commands in the shell from ruby but I can't
seem to grasp how I keep the "state" from the previous shell command.

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

Not counting "ls /dir" that is :wink:

I've tried using:

system "cd /dir"
system "ls"

..but it doesn't work.

Thanks!

Ruby provides excellent classes for this called Dir and File (and maybe FileUtils)
RDoc can be found at:
http://www.ruby-doc.org/core/classes/File.html
and
http://www.ruby-doc.org/core/classes/Dir.html

4

[dusty@dustylaptop:~] $ pwd
/Users/dusty
[dusty@dustylaptop:~] $ ls tmp/
test.txt

irb(main):003:0> system('pwd; cd tmp; ls')
/Users/dusty
test.txt
=> true

···

On Jan 7, 11:14 am, Gu stav <gus...@vonsydow.tv> wrote:

I'm trying to run multiple commands in the shell from ruby but I can't
seem to grasp how I keep the "state" from the previous shell command.

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

Not counting "ls /dir" that is :wink:

I've tried using:

system "cd /dir"
system "ls"

.but it doesn't work.

Thanks!
--
Posted viahttp://www.ruby-forum.com/.

5

two seperate calls do not work because every system-call creates a new
shell process. If you do a 'cd' the first shell does the 'cd' and is
then terminated.
The second system call starts a new shell process, which does not know
about the former cd.

You can call system("(cd /dir; ls)")

The () inside the system call executes all the commands in one shell process.

-Thomas

···

2009/1/7 Gu stav <gustav@vonsydow.tv>:

I'm trying to run multiple commands in the shell from ruby but I can't
seem to grasp how I keep the "state" from the previous shell command.

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

Not counting "ls /dir" that is :wink:

I've tried using:

system "cd /dir"
system "ls"

--
Thomas Preymesser
thopre@gmail.com

6

Works great. Thanks a million!

···

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Posted via http://www.ruby-forum.com/.

7

Here's another way to do it using a here document by having multiple commands on separate lines - much the same way as in a shell script:

robert@fussel ~
$ ruby /tmp/x.rb
+ pwd
/cygdrive/c/Dokumente und Einstellungen/robert
+ cd /tmp
+ pwd
/tmp
+ ls
x.rb

robert@fussel ~
$ cat /tmp/x.rb

system <<EOC
set -x
pwd
cd /tmp
pwd
ls
EOC

robert@fussel ~
$

Cheers

  robert

···

On 07.01.2009 19:08, dusty wrote:

On Jan 7, 11:14 am, Gu stav <gus...@vonsydow.tv> wrote:

I'm trying to run multiple commands in the shell from ruby but I can't
seem to grasp how I keep the "state" from the previous shell command.

For example, how would I perform the following sequence of commands in
ruby:

1. cd /dir
2. ls

Not counting "ls /dir" that is :wink:

I've tried using:

system "cd /dir"
system "ls"

.but it doesn't work.

Thanks!
--
Posted viahttp://www.ruby-forum.com/.

[dusty@dustylaptop:~] $ pwd
/Users/dusty
[dusty@dustylaptop:~] $ ls tmp/
test.txt

irb(main):003:0> system('pwd; cd tmp; ls')
/Users/dusty
test.txt
=> true

--
remember.guy do |as, often| as.you_can - without end