"system" call uses a different shell, or does not pick up the whole environment

Hong Yang

28 Aug 2012 28 Aug '12

10:58 a.m.

Hi, I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result. For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination directory. The code is as follows: -- module Main where import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 -- It works, except one issue that is bothering me. If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto." Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc. I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem. Can someone please help me? Thanks, Hong

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Brent Yorgey

28 Aug 28 Aug

11:08 a.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

I do not know the solution to your problem -- dealing with shells, environments, etc. can be tricky. However, do you know about the 'xargs' command? E.g. your example could be accomplished with ls | xargs -L 1 -I{} cp -pr {} destination_dir/{} -Brent On Tue, Aug 28, 2012 at 09:58:16AM -0500, Hong Yang wrote:

...

Hi,

I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result.

For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination directory.

The code is as follows:

-- module Main where

import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix

main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure

f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 --

It works, except one issue that is bothering me.

If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem.

Can someone please help me?

Thanks,

Hong

...

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Hong Yang

11:19 a.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

Hi Brent, Thanks for the xargs command info. I did not know it before. The other reason I want to play with my mapm version is eventually I want to make it concurrent. Thanks again, Hong On Tue, Aug 28, 2012 at 10:08 AM, Brent Yorgey wrote:

...

I do not know the solution to your problem -- dealing with shells, environments, etc. can be tricky.

However, do you know about the 'xargs' command? E.g. your example could be accomplished with

ls | xargs -L 1 -I{} cp -pr {} destination_dir/{}

-Brent

...
Hi,

I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result.

For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination

On Tue, Aug 28, 2012 at 09:58:16AM -0500, Hong Yang wrote: directory.

...
The code is as follows:

-- module Main where

import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix

main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure

f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 --

It works, except one issue that is bothering me.

If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem.

Can someone please help me?

Thanks,

Hong

...
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Michael Orlitzky

11:35 a.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

On 08/28/12 11:19, Hong Yang wrote:

...

Hi Brent,

Thanks for the xargs command info. I did not know it before.

The other reason I want to play with my mapm version is eventually I want to make it concurrent.

GNU Parallel is essentially xargs, run in parallel: http://www.gnu.org/software/parallel/ Might solve your problem albeit not in Haskell.

Matthew

11:40 a.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

Not to further discourage you from experimenting, but xargs can also run commands in parallel. Check out the -P argument. :) On Tue, Aug 28, 2012 at 8:19 AM, Hong Yang wrote:

...

Hi Brent,

Thanks for the xargs command info. I did not know it before.

The other reason I want to play with my mapm version is eventually I want to make it concurrent.

Thanks again,

Hong

On Tue, Aug 28, 2012 at 10:08 AM, Brent Yorgey wrote:

...
I do not know the solution to your problem -- dealing with shells, environments, etc. can be tricky.

However, do you know about the 'xargs' command? E.g. your example could be accomplished with

ls | xargs -L 1 -I{} cp -pr {} destination_dir/{}

-Brent

On Tue, Aug 28, 2012 at 09:58:16AM -0500, Hong Yang wrote:

...
Hi,

I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result.

For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination directory.

The code is as follows:

-- module Main where

import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix

main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure

f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 --

It works, except one issue that is bothering me.

If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem.

Can someone please help me?

Thanks,

Hong

...
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Hong Yang

11:49 a.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

Oh, yeah. [-P max-procs] On Tue, Aug 28, 2012 at 10:40 AM, Matthew wrote:

...

Not to further discourage you from experimenting, but xargs can also run commands in parallel. Check out the -P argument. :)

On Tue, Aug 28, 2012 at 8:19 AM, Hong Yang wrote:

...
Hi Brent,

Thanks for the xargs command info. I did not know it before.

The other reason I want to play with my mapm version is eventually I want to make it concurrent.

Thanks again,

Hong

On Tue, Aug 28, 2012 at 10:08 AM, Brent Yorgey wrote:

...
I do not know the solution to your problem -- dealing with shells, environments, etc. can be tricky.

However, do you know about the 'xargs' command? E.g. your example could be accomplished with

ls | xargs -L 1 -I{} cp -pr {} destination_dir/{}

-Brent

On Tue, Aug 28, 2012 at 09:58:16AM -0500, Hong Yang wrote:

...
Hi,

I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result.

For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination directory.

The code is as follows:

-- module Main where

import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix

main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure

f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 --

It works, except one issue that is bothering me.

If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem.

Can someone please help me?

Thanks,

Hong

...
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_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

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Brent Yorgey

12:03 p.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

Ooh, neat, I didn't even know about that option. =) On Tue, Aug 28, 2012 at 08:40:09AM -0700, Matthew wrote:

...

Not to further discourage you from experimenting, but xargs can also run commands in parallel. Check out the -P argument. :)

On Tue, Aug 28, 2012 at 8:19 AM, Hong Yang wrote:

...
Hi Brent,

Thanks for the xargs command info. I did not know it before.

The other reason I want to play with my mapm version is eventually I want to make it concurrent.

Thanks again,

Hong

On Tue, Aug 28, 2012 at 10:08 AM, Brent Yorgey wrote:

...
I do not know the solution to your problem -- dealing with shells, environments, etc. can be tricky.

However, do you know about the 'xargs' command? E.g. your example could be accomplished with

ls | xargs -L 1 -I{} cp -pr {} destination_dir/{}

-Brent

On Tue, Aug 28, 2012 at 09:58:16AM -0500, Hong Yang wrote:

...
Hi,

I am trying to mimic mapM() at shell command line. I define the interface as "mapm cmd2 cmd1," so cmd2 will be run for each of the cmd1 results. "$_" can be used inside cmd2 to represent the current cmd1 result.

For example, the command mapm 'cp -pr $_ destination_dir/$_' ls copies everything under the current directory to the destination directory.

The code is as follows:

-- module Main where

import System.Environment ( getArgs ) import System.Exit import System.IO import System.Process import Text.Regex import Text.Regex.Posix

main = do hs_argv <- getArgs if length hs_argv /= 2 then putStrLn "wrong arguments!" >> exitFailure else do let [cmd2, cmd1] = hs_argv (_, hOut, hErr, _) <- runInteractiveCommand cmd1 err <- hGetContents hErr hClose hErr if null err then do out <- hGetContents hOut mapM (f cmd2) (lines out) else putStr err >> exitFailure

f :: String -> String -> IO ExitCode f cmd2 item = system cmd2' where cmd2' = if cmd2 =~ "\\$\\_"::Bool then subRegex (mkRegex "\\$\\_") cmd2 item else cmd2 --

It works, except one issue that is bothering me.

If I issue mapm 'lt $_' ls, I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

I tried replacing "system cmd2'" with system ("source ~/.cshrc; " ++ cmd2') and system ("tcsh -c " ++ "'source ~/.cshrc; " ++ cmd2' ++ "'"), but they did not solve the problem.

Can someone please help me?

Thanks,

Hong

...
_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

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Brandon Allbery

1:12 p.m.

New subject: "system" call uses a different shell, or does not pick up the whole environment

On Tue, Aug 28, 2012 at 10:58 AM, Hong Yang wrote:

...

I get a bunch of /bin/sh: lt: command not found, while I expect it act the same as mapm 'ls -Alrt --color=auto $_' ls, because "lt" is aliased to "ls -Alrt --color=auto."

Notice "/bin/sh" above. My shell is actually tcsh. All the aliases are in ~/.cshrc.

"system"-like functions in most languages use /bin/sh specifically, regardless of the user's shell, because programs cannot be expected to adapt between the different redirection commands use by sh-like and csh-like shells. Consistency is important here, if you run a shell command from a program you do not want to deal with the fact that csh speaks an incompatible language and fish uses XML, etc. If you really want to run your/the user's shell, retrieve $SHELL from the environment and run it directly. system $ "${SHELL:-/bin/sh} -c '" ++ mycommand ++ "'" -- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

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Brandon Allbery
Brent Yorgey
Hong Yang
Matthew
Michael Orlitzky