Ruby limit on string substitutions in a backtick expression?

Question

Ok, so I am trying to execute the following code:

`#{@daemon_path} --name=#{@app_name} --command=#{@java_path} -- -jar #{jetty_jar} #{@war_path} #{random_port}`
sleep(10) #give war time to error out and die if its going to
`#{@daemon_path} --running --name=#{@app_name}`

---

The variables values are:

• @daemon_path = path/to/daemon (correct for my system)
• @app_name = foobarbazquux
• @command = path/to/java (also correct for my system)
• jetty_jar = a method that returns path to a custom jar that stands up a standalone jetty container (tested; works)
• @war_path = /path/to/helloworld/war (tested in standalone jetty container; works)
• random_port = a method that returns a random port number between 10000 and 65535 (temporarily changed it to return 8000 or 22 depending if i want to fail to start the war or not)

---

I get this error (checked commands in bash, they work fine):

Invalid arguments: no command supplied

usage: daemon [options] [--] [cmd arg...]

I fixed the above error by putting quotes around the above commands as follows:

"`#{@daemon_path} --name=#{@app_name} --command=#{@java_path} -- -jar #{jetty_jar} #{@war_path} #{random_port}`"

"`#{@daemon_path} --running --name=#{@app_name}`"

Ok, so after the code executes, i check the output with $? and notice a 0 return code. It should be 1. I ran it in bash and I get a 1. If I manually place in all of the correct values for each variable, it works correctly.

Furthermore, If i execute a script, passing in all of the values like so:

`./daemon_script_file #{@daemon_path} #{@app_name} #{@java_path} #{jetty_jar} #{@war_path} #{random_port}`

to the script daemon script file:

#!/bin/bash
set -x

d_bin=$1
name=$2
cmd=$3
jar=$4
war=$5
port=$6

$d_bin --name=$name --command=$cmd -- -jar $jar $war $port

sleep 10

$d_bin --name=$name --running

result=$?

exit $result

I get the following debug trace output:

+ d_bin=/usr/bin/daemon
+ name=
+ cmd=
+ jar=
+ war=
+ port=
+ /usr/bin/daemon --name= --command= -- -jar
+ sleep 10
+ /usr/bin/daemon --name= --running
+ result=1
+ exit 1
sh: 2: foobarbazquux: not found
invalid file (bad magic number): Exec format error

Does anyone have any clues as to why? Am i doing something incredibly stupid here?

just as a side note, the string:

"#{@daemon_path} --name=#{@app_name} --command=#{@java_path} -- -jar #{jetty_jar} #{@war_path} #{random_port}"

resolves to:

"/usr/bin/daemon  --name=foobarbazquux --command=/usr/java/jdk1.7.0_21/bin/java  -- -jar /home/nterry/JettyContainer-1.0.b4-jar-with-dependencies.jar /home/nterry/helloworld.war 8080"

Which is exactly correct

Answer 1

@Casper: You were correct. @daemon_path ended with an invalid character Thank you so much.