Bash script freezes when sent SIGINT - bash

Question

I finally grew tired of makefiles and wrote my own bash script to do my compiling. I wrote the whole thing, it works great, but for some reason, it freezes sometimes when I try to cancel it with ctrl-c. Here's the script:
#!/bin/bash
# Just to see if the script even sees the SIGINT
trap caught SIGINT
caught() { echo "hi"; }
compile() {
cpp=$(echo "$1" | sed -e 's/$/.cpp/' -e 's/^/src\//')
o=$(echo "$1" | sed -e 's/$/.o/' -e "s/^/$build_dir\//")
echo "$compile -c $cpp -o $o"
eval "$compile -c $cpp -o $o"
return $?
}
# I know this isn't normal, but I hate it when I forget to include something
# in the header and it fails way down the line
compile_h() {
h=$(echo "$1" | sed -e 's/$/.h/' -e 's/^/src\//')
o=$(echo "$1" | sed -e 's/$/.o/' -e "s/^/$build_dir\/headers\//")
echo "$compile -c $h -o /dev/null"
eval "$compile -x c++ -c $h -o $o"
if [ $? -ne 0 ]; then
return 1
fi
rm "$o"
return 0
}
build_type=$(awk 'NR==1' .build_options)
compile_command_debug=$(awk 'NR==2' .build_options)
link_command_debug=$(awk 'NR==3' .build_options)
compile_command_production=$(awk 'NR==4' .build_options)
link_command_production=$(awk 'NR==5' .build_options)
libraries=$(awk 'NR==6' .build_options)
# Make options for this build
build_dir="build"
compile="$compile_command_debug"
link="$link_command_debug"
if [ "$build_type" == "production" ]; then
build_dir="buildp"
compile="$compile_command_production"
link="$link_command_production"
fi
# These options need to be changeable later
output="game"
job_number=5
# There are more options, but they aren't important for this problem
while [ "$1" != "" ]; do
if [ "$1" == "clean" ]; then
rm -r $build_dir/*
fi
shift
done
# Get filenames
cpps=$(find src -name *.cpp | sed -e 's/src\///' -e 's/.cpp//' | sort)
hs=$(find src -name *.h | sed -e 's/src\///' -e 's/.h//' | sort)
# Ensure that all directories exist
directories=$(find src -type d | tail --lines=+2 | sed 's/src\///' | sort)
if [ ! -d "$build_dir/headers" ]; then
mkdir "$build_dir/headers"
fi
for dir in $directories; do
if [ ! -d "$build_dir/$dir" ]; then
mkdir "$build_dir/$dir"
fi
if [ ! -d "$build_dir/headers/$dir" ]; then
mkdir "$build_dir/headers/$dir"
fi
done
all_o="" # To be used for linking
# Determine what files need to be compiled
cpp_needed=""
h_needed=""
link_needed=false
# Check cpp files
for cpp_base in $cpps; do
o=$(echo "$cpp_base" | sed -e 's/$/.o/' -e "s/^/$build_dir\//")
all_o="$all_o $o"
d_file=$(echo "$cpp_base" | sed -e 's/$/.d/' -e "s/^/$build_dir\//")
if [ -f "$d_file" ]; then
d=$(<"$d_file")
d=$(echo "$d" | tr " " "\n" | tail --lines=+2 | grep "s")
if [ "$link_needed" = false ]; then
if [ "$o" -nt "$output" ]; then
link_needed=true
fi
fi
for dep in $d; do
if [ "$dep" -nt "$o" ]; then
if [ "$cpp_needed" == "" ]; then cpp_needed="$cpp_base"
else cpp_needed="$cpp_needed $cpp_base"
fi
link_needed=true
break
fi
done
else
if [ "$cpp_needed" == "" ]; then cpp_needed="$cpp_base"
else cpp_needed="$cpp_needed $cpp_base"
fi
link_needed=true
fi
done
# Check h files
for h_base in $hs; do
d_file=$(echo "$h_base" | sed -e 's/$/.d/' -e "s/^/$build_dir\/headers\//")
if [ -f "$d_file" ]; then
d=$(<"$d_file")
d=$(echo "$d" | tr " " "\n" | tail --lines=+2 | grep "s")
for dep in $d; do
if [ "$dep" -nt "$d_file" ]; then
if [ "$h_needed" == "" ]; then h_needed="$h_base"
else h_needed="$h_needed $h_base"
fi
break
fi
done
else
if [ "$h_needed" == "" ]; then h_needed="$h_base"
else h_needed="$h_needed $h_base"
fi
fi
done
# Compile
did_something=false
# Compile hs
while [ "$h_needed" != "" ]; do
for index in $(seq 1 $job_number); do
if [ "$h_needed" == "" ]; then break; fi
if ! kill -0 ${pids[index]} 2>/dev/null; then
new_file=$(echo "$h_needed" | awk '{print $1;}')
if [ $(echo "$h_needed" | wc -w) -eq 1 ]; then h_needed=""
else h_needed=$(echo "$h_needed" | cut -d " " -f2-)
fi
compile_h "$new_file" &
pids[index]=$!
did_something=true
fi
done
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done
while [ $(pgrep -c -P$$) -gt 0 ]; do
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done
# Compile cpps
while [ "$cpp_needed" != "" ]; do
for index in $(seq 1 $job_number); do
if [ "$cpp_needed" == "" ]; then break; fi
if ! kill -0 ${pids[index]} 2>/dev/null; then
new_file=$(echo "$cpp_needed" | awk '{print $1;}')
if [ $(echo "$cpp_needed" | wc -w) -eq 1 ]; then cpp_needed=""
else cpp_needed=$(echo "$cpp_needed" | cut -d " " -f2-)
fi
compile "$new_file" &
pids[index]=$!
did_something=true
fi
done
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done
while [ $(pgrep -c -P$$) -gt 0 ]; do
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done
# Compile program
if [ "$link_needed" = true ]; then
echo "$link $all_o -o game $libraries"
eval "$link $all_o -o game $libraries"
did_something=true
fi
# Make a message if nothing compiled
if [ "$did_something" = false ]; then
echo "Program is already compiled."
fi
It normally works perfectly. However, sometimes, when I try to cancel it with ctrl-c it just freezes. With a bit of debugging I saw that when the script wasn't setting up a new job, ctrl-c would work just fine. But when it was in the middle of setting up a new job, it would freeze the script. It wouldn't even catch the SIGINT (which that "echo hi" thing is for at the top). I honestly have no idea what's going on. Does anybody know what's going on? Thank you!
Edit: I realized I should probably mention I use g++ to compile.
Edit again: Here's an even-more stripped down version of the script. You would still need to setup some files to compile if you wanted to test it:
#!/bin/bash
# Just to see if the script even sees the SIGINT
trap caught SIGINT
caught() { echo "hi"; }
# I know this isn't normal, but I hate it when I forget to include something
# in the header and it fails way down the line
compile_h() {
h=$(echo "$1" | sed -e 's/$/.h/' -e 's/^/src\//')
o=$(echo "$1" | sed -e 's/$/.o/' -e "s/^/$build_dir\/headers\//")
echo "$compile -c $h -o /dev/null"
eval "$compile -x c++ -c $h -o $o"
if [ $? -ne 0 ]; then
return 1
fi
rm "$o"
return 0
}
build_type="debug"
build_dir="build"
compile="g++"
job_number=5
# Get filenames
hs=$(find src -name *.h | sed -e 's/src\///' -e 's/.h//' | sort)
h_needed=$(echo $hs)
# Compile hs
while [ "$h_needed" != "" ]; do
for index in $(seq 1 $job_number); do
if [ "$h_needed" == "" ]; then break; fi
if ! kill -0 ${pids[index]} 2>/dev/null; then
new_file=$(echo "$h_needed" | awk '{print $1;}')
if [ $(echo "$h_needed" | wc -w) -eq 1 ]; then h_needed=""
else h_needed=$(echo "$h_needed" | cut -d " " -f2-)
fi
compile_h "$new_file" &
pids[index]=$!
did_something=true
fi
done
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done
while [ $(pgrep -c -P$$) -gt 0 ]; do
wait -n
if [ $? -ne 0 ]; then
wait
exit 1
fi
done

Answer 1

Any program that you run in your script may override your trap and set up its own. That trap might for example crash the currently running program for some reason. When this happens, take a look at the process tree in ps wafux to find the most likely culprit. For example, a zombie (Z) or uninterruptible sleep (D) process state (see man ps) is common when a process isn't going anywhere.