Porting a Bash Script to Java

Question

I'm attempting to emulate the functionality of the bash shell script below using a Process or ProcessBuilder object in Java. It's not 100% clear to me how I do the redirection for standard-in. How can I accomplish this?

#
#  Redirect shell echo command from standard output to file
#  This will construct the input file
# 
exec 1> $STDIN
echo -e "$NFILE\n$GFILE\n$INPUT\n$OUTPUT\n$CAX"
exec 1>&-

#
#  Run executable redirecting standard in as the input file and output to a log file
#
"$EXE" < $STDIN >& $LOG

why exec 1> $STDIN ? Why not just echo -e "..." > $STDIN — mob
– mob, Commented Sep 22, 2009 at 15:51
@mobrule Not sure. I inherited the script. What does exec 1 do differently? — javacavaj
– javacavaj, Commented Sep 23, 2009 at 15:17

Community · Accepted Answer · 2017-05-23 10:27:36Z

2

The Process object streams are misleadingly named. You need to write to the OutputStream of the Process object.

From the doc:

All its standard io (i.e. stdin, stdout, stderr) operations will be redirected to the parent process through three streams (Process.getOutputStream(), Process.getInputStream(), Process.getErrorStream()).

You also have to consume the process output and standard error concurrently, otherwise buffers will fill up and the process will block. See here for more information.

edited May 23, 2017 at 10:27

CommunityBot

11 silver badge

answered Sep 22, 2009 at 15:49

Brian Agnew

273k38 gold badges342 silver badges443 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Porting a Bash Script to Java

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related