#acl All:read

/* DO NOT EDIT THIS FILE! moinconfig/cspages/AlamodeAccessCaveatsAndWarnings! */
<<TableOfContents()>>

<<Anchor(randomdat)>>
= Trace File Arguments Are Not Always Files =
In practically all programming assignments, at least one command line argument is a file from which `SIM` should read random values from (in lieu of using a library specific pRNG).  The [[Assignments/TraceFiles|TraceFiles]] page has sample files for use in development.

'''Beware''' that `grader.sh` scripts don't usually provide a static regular file as these arguments!
Instead they use input redirection to connect a program generating '''a possibly infinite''' sequence of values to your `SIM`.
This means that if you attempt to read all random values into an array or list, your `SIM` is going to "hang" --- it will dutifully read in an infinite collection of `double`s until you exhaust machine memory.

An easy way to manage this is to create a `TraceFile` object that accepts a filename as a constructor parameter and provides a single `getRandom()` member function that returns a floating point value.  Of simply write a `getRandom( tracefile )` global function that accepts an open file descriptor (object, pointer, handle, the terminology depends on the language) and returns the next `double` from the file.

== Why are things so complicated you ask? ==
By using redirection as the source for your `SIM` random numbers, `grader.sh` can be written with tests to be sure the random numbers are being used properly,<<FootNote(Depending on the system being modeled)>> it is easy to incorporate pRNG '''streams''' into the mix without worrying about which language a student is using, and by providing fake sequence of random values...
{{{
$ ./SIM <(yes 0.5)
}}}
certain types of '''consistency checks''' can be automated without micro-managing how student programs are written.

<<Anchor(missinglibs)>>
= Missing Libraries on An alamode Machine =
Occasionally, you will login to an `alamode` machine and some course provided code will fail to run due some '''very bizarre''' reasons
{{{
ctb60-12$ ~khellman/SIMGRADING/Random 12345
/usr/lib/libssl.so: No such file or directory
}}}
Of course, `libssl.so` is there:
{{{
ctb60-12$ file /usr/lib/libssl.so /usr/lib/libssl.so.1.1
/usr/lib/libssl.so:     symbolic link to libssl.so.1.1
/usr/lib/libssl.so.1.1: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=5a12e36d18f5fd2e5519bd1f7741bcc6907bb3ad, stripped
}}}
This seems to be resolved by '''using a different''' `alamode` machine.  `ctb60-12` won't be fixed until it gets a reboot :(


<<Anchor(sshXhopping)>>
= Grrr, I can't see the PDFs generated by grader.sh =
Use a PDF viewer installed on the alamode images.  Some examples include `gview` or `evince`; but `xpdf` is '''by the far the fastest'''.
{{{
$ xpdf output-1010.pdf
}}}

If you are `ssh(1)`ing into alamode, use the `-X` option.
{{{
remote-with-vpn$ ssh -X ctb60-13.mines.edu
ctb60-13$ gview output-1010.pdf
}}}