Multiple commands in shell

[Gu stav]

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

I've tried using:

system "cd /dir"
system "ls"

..but it doesn't work.

Thanks!

 

[Sebastian Hungerecker]

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

 

[Jan-Erik R.]

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

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

 

[Gu stav]

Works great. Thanks a million!

 

[dusty]

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

I've tried using:

system "cd /dir"
system "ls"

.but it doesn't work.

Thanks!

[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

 

[Thomas Preymesser]

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

I've tried using:

system "cd /dir"
system "ls"

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

 

[Robert Klemme]

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

I've tried using:

system "cd /dir"
system "ls"

.but it doesn't work.

Thanks!

[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

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