Make more POSIX compliant

This replaces most calls to `echo` with `printf` to improve
compatibility. This also replaces the bash-specific double bracket
test conditional with the POSIX compliant single bracket.

1 files changed, 25 insertions, 28 deletions

diff --git a/crypttab b/crypttab
index 706e2f1..8833a72 100755
--- a/crypttab
+++ b/crypttab
@@ -1,4 +1,7 @@
 #!/usr/bin/env bash
+set -euo pipefail
+export IFS=$'\n\t'
+
 #
 # A script that handles basic crypttab functionality to mount encrypted volumes
 # on execution.
@@ -14,14 +17,14 @@ TAB=/etc/crypttab
 # them first, since not doing so will cause the luksClose to hang.
 #
 function destroy_entries {
-  if [[ ! -f ${TAB} ]]; then
-    echo "Could not access ${TAB}."
+  if [ ! -f "${TAB}" ]; then
+    printf 'Could not access %s.\n' "${tab}"
     exit 1
   fi
 
   # For each entry in crypttab
   while read entry; do
-    local name=${entry%% *}
+    local name="${entry%% *}"
 
     # Unmount all mountpoins if mounted anywhere
     # Cryptsetup luksClose will repeatedly fail if the devices is mounted
@@ -29,22 +32,21 @@ function destroy_entries {
     for i in "$(mount | grep /dev/mapper/${name})"; do
       local mntpoint=$(echo ${i} | tr -s ' ' | cut -d ' ' -f 3)
       # Skip if empty
-      [[ ${mntpoint} == '' ]] && continue
+      [ "${mntpoint}" == '' ] && continue
 
-      echo "${name} mounted at ${mntpoint}. Unmounting"
+      printf '%s mounted at %s. Unmounting\n' "${name}" "${mntpoint}"
 
       # Kill any running processes accessing mntpoint
       for pid in $(lsof -t ${mntpoint}); do
         pidstr=$(ps -f ${pid} | tail -n 1)
-        echo "Halting ${pid} ${pidstr##* }"
-        kill ${pid}
+        printf 'Halting %s %d\n' "${pid}" "${pidstr##* }"
+        kill "${pid}"
       done
 
       # Unmount
-      umount ${mntpoint}
+      umount "${mntpoint}"
     done
-
-    cryptsetup luksClose ${name}
+    cryptsetup luksClose "${name}"
   done < "${TAB}"
 }
 
@@ -56,8 +58,8 @@ function destroy_entries {
 function stat_entries {
   local _name # Name of the mount
   local _dev  # Device to be decrypted
-  if [[ ! -f ${TAB} ]]; then
-    echo "Could not access ${TAB}."
+  if [ ! -f "${tab}" ]; then
+    printf 'Could not access %s.\n' "${tab}"
     exit 1
   fi
 
@@ -66,10 +68,10 @@ function stat_entries {
     _name=$(echo ${line} | tr -s ' ' | cut -d ' ' -f 1)
     _dev=$(echo ${line} | tr -s ' ' | cut -d ' ' -f 2)
 
-    if [[ -L /dev/mapper/${_name} ]]; then
-      echo "${_name} (${_dev}) decrypted at /dev/mapper/${_name}"
+    if [ -L "/dev/mapper/${name}" ]; then
+      printf '%s decrypted at /dev/mapper/%s\n' "${_dev}" "${_name}"
     else
-      echo "${_name} (${_dev}) not decrypted."
+      printf '%s not decrypted\n' "${_dev}"
     fi
   done < "${TAB}"
 }
@@ -82,8 +84,8 @@ function setup_entries {
   local _dev  # Encrypted device path
   local _key  # Encryption key to decrypt the device with
 
-  if [[ ! -f ${TAB} ]]; then
-    echo "Could not access ${TAB}."
+  if [ ! -f "${tab}" ]; then
+    printf 'Could not access %s.\n' "${tab}"
     exit 1
   fi
 
@@ -91,17 +93,12 @@ function setup_entries {
     _name=$(echo ${entry} | tr -s ' ' | cut -d ' ' -f 1)
     _dev=$(echo ${entry} | tr -s ' ' | cut -d ' ' -f 2)
     _key=$(echo ${entry} | tr -s ' ' | cut -d ' ' -f 3)
-
-    # Skip any devices that are already decrypted
-    if [ -b "/dev/mapper/${_name}" ]; then
-      printf "Device ${_dev} already decrypted at /dev/mapper/${_name}.\n"
-      continue
-    fi
-    echo "Decrypting ${_dev} using key ${_key}."
-    echo "Plaintext device is at /dev/mapper/${_name}"
-    cryptsetup luksOpen ${_dev} ${_name} --key-file ${_key}
-
-  done < "${TAB}"
+  
+    printf 'Decrypting %s using key %s.\n' "${_dev}" "${_key}"
+    printf 'Plaintext device is at /dev/mapper/%s\n' "${_name}"
+    cryptsetup luksOpen "${_dev}" "${_name}" --key-file "${_key}"
+  done
+  done < "${tab}"
 }