How do you format output string in bash script for input by another script? - linux

Question

I need to unzip a bunch of student assignment (jar) files so that I can use a script to submit the contents to the Moss (Stanford) plagiarism detection server. I did the same thing in Java which was trivial but I'm trying to re-implement to as a bash script.
I am trying to do the following:
Get a list of student names (each student has a directory).
In each student directory, sub-directories exist numbered from 1 to the
latest submission. I need to get the directory with the highest
number.
Inside of each of those submission directories contains a
jar file that I need. I copy each jar into a temp directory with the
same name as the student and unzip it.
I need that temp directory listing formatted as a string in the form
/tempDir/studentName1/.languageExt /tempDir/studentName2/.languageExt
The student directory has the basic structure:
Student_Root_Directory:
Student1
Student2
Student1
Sub-Directories: 1 2 3 4 5
1: student1.jar
2: student1.jar
...
Student2
Sub-Directories: 1 2 3
1. student2.jar
...
To do the first 3 steps above I did:
#!/bin/bash
# Extract all jar files into a temp directory called /home/moss/tempJarFiles/studentName
# $1 is the command line argument that contains the path to the institution submission dir.
# $2 is the language extension: .c, .cpp, .java, .py
students=`ls $1`
student_dir=$1
languageExt=$2
mossDir="/home/moss"
tempDir="/home/moss/tempJarStorage"
for student in $students
do
latestSubmissionDir=`ls -t $student_dir/$student | head -1`
for jarDir in $latestSubmissionDir
do
mkdir $tempDir/$student
cp $student_dir/$student/$jarDir/*.jar $tempDir/$student
unzip -d $tempDir/$student/ -o -j $tempDir/$student/$student.jar *.$languageExt
rm $tempDir/$student/$student.jar
done
done
...which results in a number of student directories being created in a temp directory that contains only the unzipped contents for the student submissions.
I need the ls output of the new temp directories formatted as a string that contains:
/tempDir/studentName1/\*.languageExt /tempDir/studentName2/\*.languageExt
I have tried variations on
find "$tempDir" -iname "*.$languageExt" -printf "%p/*.$languageExt"
using iname and not - but I either have output that contains extra directory information such as $tempDir/*.languageExt (when I just need the subdirectories $tempDir/$studentName/*.languageExt) or I have output where the path for every source file is also listed such as:
$tempDir/$studentName/studentNameA.java
$tempDir/$studentName/studentNameB.java
when I only need
$tempDir/$studentName/*.java
I think this should be really easy and I'm just over thinking it. Any hints for improving the script also appreciated.

Answer 1

Here's a revised version of the script hat may work:
#/bin/bash
# Extract all jar files into a temp directory called /home/moss/tempJarFiles/studentName
# $1 is the command line argument that contains the path to the institution submission dir.
# $2 is the language extension: c, cpp, java, py
students_dir=$1
languageExt=$2
studentPathsT=( "$students_dir"/*/ )
mossDir='/home/moss'
tempDir='/home/moss/tempJarStorage'
for studentPathT in "${studentPathsT[#]}"; do
student=$(basename "$studentPathT")
mkdir "$tempDir/$student"
submissionDirsT=( "$studentPathT"*/ )
latestSubmissionDirT=${submissionDirsT[${#submissionDirsT[#]-1]}
cp "$latestSubmissionDirT"*.jar "$tempDir/$student/"
unzip -d "$tempDir/$student/" -o -j "$tempDir/$student/*.jar" "*.$languageExt"
rm "$tempDir/$student"/*.jar
done
# Note that at this point `"$tempDir"/*/*.$languageExt` would expand
# to all extracted submission files, across all students.
# Finally, output each student's extracted files as an unexpanded glob à la
# /{tempDir}/{studentName1}/*.{languageExt}
for pT in "$tempDir"/*/; do
echo "$pT*.$languageExt"
# Note: If there is a chance that your filenames contain
# embedded newlines (rare in practice) using `echo` won't work properly
# as #Charles Duffy points out.
# If that is a concern, use
# printf '%s\0' "$pT*.$languageExt"
# and process the output with a utility that can process NUL characters
# as separators, such as `xargs -0`.
done
It avoids using ls and only uses pathname expansion and array variables so as to properly deal with paths that contain embedded spaces and other shell metacharacters.
suffix ...T in variable names indicates that a particular path or array of paths is *T*erminated, i.e, that it ends in a /.
The assumption is that the numbered subdirectories do not go beyond 9, as the implicit lexical sorting of pathname expansion is relied upon; if the numbers go higher, explicit numerical sorting must be applied.
Note that the globs (pathname patterns) passed to unzip are intentionally double-quoted, as they should be interpreted by unzip, not the shell.
Note that, based on your original code, I've assumed that $languageExt does NOT start with . (e.g., cpp rather than .cpp), despite what your comment says.