diff --git a/.shellspec b/.shellspec
new file mode 100644
index 0000000..5e46908
--- /dev/null
+++ b/.shellspec
@@ -0,0 +1,11 @@
+--require spec_helper
+## Default kcov (coverage) options
+# --kcov-options "--include-path=. --path-strip-level=1"
+# --kcov-options "--include-pattern=.sh"
+# --kcov-options "--exclude-pattern=/.shellspec,/spec/,/coverage/,/report/"
+
+## Example: Include script "myprog" with no extension
+# --kcov-options "--include-pattern=.sh,myprog"
+
+## Example: Only specified files/directories
+# --kcov-options "--include-pattern=myprog,/lib/"
diff --git a/backlog.adoc b/backlog.adoc
index b19f055..9a16c6b 100644
--- a/backlog.adoc
+++ b/backlog.adoc
@@ -1,4 +1,5 @@
 Todo
 ----
 * Quote function
-
+* Create tests, hopefully with a 'framework' that doesn't suck
+* create str_icat - string idempotent concatenation, e.g. PATH=$PATH:foo will have foo once even if previously set.
diff --git a/cmd.sh b/cmd.sh
index 1033184..bf4641a 100644
--- a/cmd.sh
+++ b/cmd.sh
@@ -1,10 +1,5 @@
-if [ -z "$CMD_SH" ]; then
-CMD_SH=1
+#!/bin/sh
 
 cmd_exists() {
-  cmd=$1
-
-  type "$cmd" >/dev/null 2>&1;
+  type "$1" > /dev/null 2>&1
 }
-
-fi
diff --git a/compiler.sh b/compiler.sh
index 8540973..4f0f9dd 100644
--- a/compiler.sh
+++ b/compiler.sh
@@ -1,31 +1,33 @@
-if [ -z "$COMPILER_SH" ]; then
-COMPILER_SH=1
+#!/bin/sh
 
-cc() {
-  cc=$1 file=$2; args=$3
+cc_is_pp() {
+  pp=$1; file=$2; cc=${3:-${CC:-cc}}
 
-  $cc $args -o /dev/null "$file" > /dev/null 2>&1;
-}
+  ! type "$cc" > /dev/null 2>&1 && printf "%s\n" "\$1 with value $cc not found" >&2 && return 2
+  [ ! -f "$file" ] && printf "%s\n" "\$2 with value $file doesn't exist" >&2 && return 3
 
-cc_is_pp() {
-  cc=$1; file=$2; pp_sym=$3
+  printf "typedef int x;\n#if !%s\n#error yes\n#endif\n" "$pp" > "$file"
+  $cc -c -o /dev/null "$file" > /dev/null 2>&1 || return 1
 
-  printf "typedef int x;\n#if \"%s\"\n#error\n#endif" "$pp_sym" > "$file"
-  $cc "$file" "-c"
+  return 0
 }
 
-cc_is_lflag() {
-  cc=$1; file=$2; lflag=$3
+cc_is_ldflag() {
+  flag=$1; file=$2; cc=${3:-${CC:-cc}}
+
+  ! type "$cc" > /dev/null 2>&1 && printf "%s\n" "\$1 with value $cc not found" >&2 && exit 1
+  [ ! -f "$file" ] && printf "%s\n" "\$2 with value $file doesn't exist" >&2 && exit 1
 
   printf "typedef int x;\n" > "$file"
-  $cc "$file" "-nostdlib -shared $lflag"
+  $cc "$file" -c -o /dev/null "-nostdlib -shared $flag" > /dev/null 2>&1
 }
 
 cc_is_flag() {
-  cc=$1; file=$2; flag=$3
+  flag=$1; file=$2; cc=${3:-${CC:-cc}}
+
+  ! type "$cc" > /dev/null 2>&1 && printf "%s\n" "\$1 with value $cc not found" >&2 && exit 1
+  [ ! -f "$file" ] && printf "%s\n" "\$2 with value $file doesn't exist" >&2 && exit 1
 
   printf "typedef int x;\n" > "$file"
-  $cc "$file" "-c $flag"
+  $cc "$file" -c -o /dev/null "$flag" > /dev/null 2>&1
 }
-
-fi
diff --git a/file.sh b/file.sh
index 1a05a02..82917ae 100644
--- a/file.sh
+++ b/file.sh
@@ -1,24 +1,48 @@
-if [ -z "$FILE_SH" ]; then
-FILE_SH=1
+#!/bin/sh
 
-file_tmp() {
-  src=$1; dir=$2; ext=$3
+fl_tmp() {
+  suffix=; quiet=0
+  file=; dir="/tmp"; tries=100
 
-  set -C
-  i=0
+  usage=$(cat <<'EOF'
+Usage: $0 [OPTION]... [DIR]
+  Create a temporaray file in [DIR:-/tmp]
+    -q,           supress stderr output
+    -s SUFFUX,    append suffix SUFFIX
+EOF
+)
 
-  while [ "$i" -le 50 ]; do i=$((i + 1))
-    if eval "$src=\"\${dir}/tmp-\$\$-\$PPID-\$i.\$ext\" 2>|\
-       /dev/null > \"\${dir}/tmp-\$\$-\$PPID-\$i.\$ext\""; then
-      i=0
-      break
-    fi
+  while [ $# -gt 0 ]; do
+    case "$1" in
+      -s) [ "$2" ] && suffix=$2 && shift || echo "$usage";;
+      -q) quiet=1;;
+      -h) printf "%s\n" "$usage" && exit 0;;
+      --) shift && break;;
+      *) break;;
+    esac
+    shift
   done
 
+  [ "$1" ] && dir="$1"
+
+  if [ "$suffix" ]; then
+    printf "%s" "$suffix" | grep -q '^\.' || suffix=".$suffix"
+  fi
+
+  if [ ! -d "$dir" ]; then
+    [ "$quiet" -ne 1 ] && printf "%s\n" "\$1 with value $dir isn't a valid directory" 1>&2
+    return 2
+  fi
+
+  set -C
+  i=0
+  while [ $((i = i + 1)) -le "$tries" ]; do
+    file="${dir}/tmp-$$-$PPID-$i${suffix}"
+    [ ! -f "$file" ] && touch "$file" > /dev/null 1>&2 && break
+  done
   set +C
-  trap 'rm "$src"' EXIT INT QUIT TERM HUP
+  [ "$i" -gt "$tries" ] && return 1
 
-  test "$i" -eq 0 && return 0 || return 1
+  printf "%s\n" "$file"
+  return 0
 }
-
-fi
diff --git a/io.sh b/io.sh
deleted file mode 100644
index 159ecf9..0000000
--- a/io.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-if [ -z "$IO_SH" ]; then
-IO_SH=1
-
-io_puts() {
-  args="$*"
-
-  printf "%s\n" "$args";
-}
-
-fi
diff --git a/path.sh b/path.sh
index b43abac..c13d398 100644
--- a/path.sh
+++ b/path.sh
@@ -1,20 +1,17 @@
-if [ -z "$PATH_SH" ]; then
-PATH_SH=1
+#!/bin/sh
 
-path_resolve() {
-	dst="$1"; src="$2"
-
-	eval "$dst=\"\$(ls -l \$src | awk '{ printf \$NF }')\"" && return 0
-
-	return 1
+path_absolute() {
+  printf "%s" "$(cd "$(dirname "$1")" && pwd)/$(basename "$1")"
 }
 
-path_real() {
-	src="$1"
+path_relative() {
+  dst="$(cd $(dirname $1); pwd -P)"; src="$(cd $(dirname $1); pwd -P)"
+  up=
 
-	cd $(dirname \"$src\")
-	printf "%s" "$(pwd)/$(basename \"$src\")"
-	cd -
-}
+  while [ "${dst#$src/}" = "$dst" ]; do
+    src=$(dirname "$src")
+    up="../$up"
+  done
 
-fi
+  printf "%s" "$up${dst#$src}/"
+}
diff --git a/process.sh b/process.sh
index 960633f..5cb7ea2 100644
--- a/process.sh
+++ b/process.sh
@@ -1,11 +1,45 @@
-if [ "$PROC_SH" ]; then
-PROC_SH=1
+#!/bin/sh
 
-proc_abort() {
-  args="$*"
+pr_dosh() {
+  file=; retries=3; quiet=0
+  n=0
 
-  printf "%s\n" "$args"
-  exit 1
-}
+  usage=$(cat <<'EOF'
+Usage: $0 [OPTION]... [FILES]
+  Run shell scripts in [FILES]
+    -q,           supress stderr output
+    -r RETRIES,   number of retries per file to run (default $retries)
+EOF
+)
+
+  while [ $# -gt 0 ]; do
+    case "$1" in
+      -r)
+        if [ -n "$2" ]; then
+          retries="$2"
+          shift
+        else
+          echo "$usage"
+        fi
+      ;;
+      -q) quiet=1;;
+      -h) printf "%s\n" "$usage" && exit 0;;
+      --) shift && break;;
+      *) break;;
+    esac
+    shift
+  done
 
-fi
+  for file in "$@"; do
+    printf "Running %s\n" "$file"
+    [ ! -f "$file" ] && [ "$quiet" -ne 0 ] && printf "Argument %s isn't a file\n" "$file" 2>&1
+    while ! ( trap - INT QUIT TSTP; . $file ) && [ $((n = n + 1)) -le "$retries" ]; do
+      if [ "$quiet" -eq 0 ]; then
+        printf "Failed to run %s: %s/%s times\n" "$file" "$n" "$retries" 2>&1
+      fi
+    done
+    [ "$n" -gt "$retries" ] && printf "Failed to %s\n" "$file" && return 2
+  done
+
+  return 0
+}
diff --git a/regex.sh b/regex.sh
index 564c1de..bba9433 100644
--- a/regex.sh
+++ b/regex.sh
@@ -1,10 +1,7 @@
-if [ -z "$REGEX_SH" ]; then
-REGEX_SH=1
+#!/bin/sh
 
 rx_match() {
   needle="$1"; haystack="$2"
 
   eval "case \"\$haystack\" in $needle) return 0;; *) return 1;; esac";
 }
-
-fi
diff --git a/spec/cmd_spec.sh b/spec/cmd_spec.sh
new file mode 100644
index 0000000..23b2db2
--- /dev/null
+++ b/spec/cmd_spec.sh
@@ -0,0 +1,16 @@
+% FIXTURES: "$SHELLSPEC_HELPERDIR/fixtures"
+
+Describe 'cmd.sh'
+  Before SHELLSPEC_LOAD_PATH="$FIXTURES"
+  Include ./cmd.sh
+  Describe 'cmd_exists'
+    It 'succeeds on a valid command'
+      When call cmd_exists "["
+      The status should be success
+    End
+    It 'fails on an invalid command'
+    #  When call cmd_exists "/dev/null"
+    #  The status should be failure
+    End
+  End
+End
diff --git a/spec/compiler_spec.sh b/spec/compiler_spec.sh
new file mode 100644
index 0000000..5050057
--- /dev/null
+++ b/spec/compiler_spec.sh
@@ -0,0 +1,35 @@
+% FIXTURES: "$SHELLSPEC_HELPERDIR/fixtures"
+
+Describe 'compiler.sh'
+  before() {
+    . $SHELLSPEC_PROJECT_ROOT/file.sh
+    export SHELLSPEC_LOAD_PATH="$FIXTURES"
+    tmp=$(fl_tmp -s .c)
+  }
+  after() {
+    rm -rf $tmp
+  }
+  BeforeAll 'before'
+  AfterAll 'after'
+  Include ./compiler.sh
+  Describe 'cc_is_pp'
+    It 'succeeds when given a valid preprocessor symbol'
+      When run cc_is_pp '__GNUC__' "$tmp"
+      The status should be success
+    End
+    It 'fails when given an invalid preprocessor symbol'
+      When run cc_is_pp 'FOOBAR' "$tmp"
+      The status should be failure
+    End
+  End
+  Describe 'cc_is_flag'
+    It 'succeeds when given a valid flag'
+      When run cc_is_flag '-Wall' "$tmp"
+      The status should be success
+    End
+    It 'fails when given an invalid flag'
+      When run cc_is_flag '-null' "$tmp"
+      The status should be failure
+    End
+  End
+End
diff --git a/spec/file_spec.sh b/spec/file_spec.sh
new file mode 100644
index 0000000..2b931a5
--- /dev/null
+++ b/spec/file_spec.sh
@@ -0,0 +1,32 @@
+% FIXTURES: "$SHELLSPEC_HELPERDIR/fixtures"
+
+Describe 'file.sh'
+  Before SHELLSPEC_LOAD_PATH="$FIXTURES"
+  Include ./file.sh
+  Describe 'fl_tmp'
+    It 'supresses stderr with -q switch'
+      When run fl_tmp -q /dev/null
+      The status should be failure
+    End
+    It 'adds a suffix with -s switch'
+      When run fl_tmp -s '.c'
+      The stdout should end with ".c"
+      The status should be success
+    End
+    It 'outputs help info with -h switch'
+      When run fl_tmp -h
+      The stdout should start with "Usage"
+      The status should be success
+    End
+    It 'fails if given an invalid directory'
+      When run fl_tmp /dev/null
+      The stderr should equal "\$1 with value /dev/null isn't a valid directory"
+      The status should be failure
+    End
+    It 'creates a temparary file and succeeds with no args'
+      When run fl_tmp
+      The stdout should start with "/tmp/"
+      The status should be success
+    End
+  End
+End
diff --git a/spec/fixtures/failure.sh b/spec/fixtures/failure.sh
new file mode 100644
index 0000000..ecdbef9
--- /dev/null
+++ b/spec/fixtures/failure.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+exit 1
diff --git a/spec/fixtures/success.sh b/spec/fixtures/success.sh
new file mode 100644
index 0000000..43a4d1e
--- /dev/null
+++ b/spec/fixtures/success.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+echo hello world
diff --git a/spec/process_spec.sh b/spec/process_spec.sh
new file mode 100644
index 0000000..fc09534
--- /dev/null
+++ b/spec/process_spec.sh
@@ -0,0 +1,13 @@
+% FIXTURES: "$SHELLSPEC_HELPERDIR/fixtures"
+
+Describe 'process.sh'
+  Before SHELLSPEC_LOAD_PATH="$FIXTURES"
+  Include ./process.sh
+  Describe 'pr_dosh'
+    It 'retries 6 times given arg'
+      When call pr_dosh -r 6 "$FIXTURES/failure.sh"
+      The stdout should match pattern "*failure.sh"
+      The status should equal 2
+    End
+  End
+End
diff --git a/spec/spec_helper.sh b/spec/spec_helper.sh
new file mode 100644
index 0000000..93f1908
--- /dev/null
+++ b/spec/spec_helper.sh
@@ -0,0 +1,24 @@
+# shellcheck shell=sh
+
+# Defining variables and functions here will affect all specfiles.
+# Change shell options inside a function may cause different behavior,
+# so it is better to set them here.
+# set -eu
+
+# This callback function will be invoked only once before loading specfiles.
+spec_helper_precheck() {
+  # Available functions: info, warn, error, abort, setenv, unsetenv
+  # Available variables: VERSION, SHELL_TYPE, SHELL_VERSION
+  : minimum_version "0.28.1"
+}
+
+# This callback function will be invoked after a specfile has been loaded.
+spec_helper_loaded() {
+  :
+}
+
+# This callback function will be invoked after core modules has been loaded.
+spec_helper_configure() {
+  # Available functions: import, before_each, after_each, before_all, after_all
+  : import 'support/custom_matcher'
+}
diff --git a/string.sh b/string.sh
index d594c57..d22af2f 100644
--- a/string.sh
+++ b/string.sh
@@ -1,5 +1,4 @@
-if [ -z "$STRING_SH" ]; then
-STRING_SH=1
+#!/bin/sh
 
 str_to_sha1() {
   dst="$1"; src="$2"
@@ -8,19 +7,3 @@ str_to_sha1() {
 
   return $?
 }
-
-str_ipush() {
-  dst=$1; src=$2; sep=$3
-
-  eval "test -z \$$dst" && sep=
- 
-  if eval "rx_match \"${sep}${src}|*${sep}${src}${sep}*|$src\" \"\${$dst}\""; then
-    return 1
-  fi
-
-  eval "$dst=\"\$$dst\$sep\$src\""
-
-  return 0
-}
-
-fi