*Self-review for the follow-up question, which I will post in the following days.*
# Treat unset variables as an error when substituting
Add this to the beginning of the script:
set -o nounset
# `[ "$#" -eq 0 ]` instead of `[ -z "$1" ]`
It seems testing number of arguments is a better approach than testing if the first argument is set. Also, I added:
[ "$#" -gt 1 ] && echo "Multiple arguments are not supported!" && exit 1
for an obvious reason.
# As pointed out by Janos, put password file path into variable
And put it in the beginning of the script (maybe with a comment).
# In order to compress many directories with the same password,
# I decided to create a password file to avoid too many annoying prompts
passwd_file="/home/vlastimil/.blablablabla"
# Test for the existence of the password file
It may happen that you migrate to a different platform and / or accidentally delete the file.
[ ! -f "$passwd_file" ] && echo "The password file does not exist!" && exit 1
# You should also test for existence of the processed files
Like this, the comments are optional:
# TAR is archiving the directory into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}" ] && echo "File ${backup_file} exists, exiting." && exit 1
# XZ is compressing the archive into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}.xz" ] && echo "File ${backup_file}.xz exists, exiting." && exit 1
# OpenSSL is decrypting the file (for verification) into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}.xz.dec" ] && echo "File ${backup_file}.xz.dec exists, exiting." && exit 1
# OpenSSL is encrypting the compressed file into the following permanent file,
# this is the result of successful processing
[ -f "${backup_file}.xz.enc" ] && echo "File ${backup_file}.xz.enc exists, exiting." && exit 1
# SHA512SUM is computing a hash sum of the encrypted file into the following permanent file,
# this is the result of successful processing
[ -f "${backup_file}.xz.enc.SHA512SUM" ] && echo "File ${backup_file}.xz.enc.SHA512SUM exists, exiting." && exit 1
# Define all common colors (optional)
It happens one might like a change and / or later wants to re-define the styling. So this may be good idea, just comment out the colors that you don't use.
red=$(tput setaf 1)
blue=$(tput setaf 4)
cyan=$(tput setaf 6)
green=$(tput setaf 2)
white=$(tput setaf 7)
yellow=$(tput setaf 3)
magenta=$(tput setaf 5)
# As pointed out by Janos, color definitions should be renamed
> I would rename bold_red and bold_yellow to be more about the purpose than presentation.
And I agree:
action_number_color="${bold}${red}"
action_color="${bold}${yellow}"
file_color="${bold}${white}"
success_color="${bold}${green}"
# Again, as pointed out by Janos, there should be a helper printing function
> A helper function would be more convenient to print the headers for the steps, instead of blocks of `echo`s.
Like this, I added some leading and trailing coloring:
print_action()
{
echo
echo "${action_number_color}$1${no_color}"
echo
}
# There could be a helper error function too
For instance:
print_error()
{
echo
echo "$1"
exit 1
}
# There are too long lines of strings
Both in the code, and in the output. It could be simplified for example:
print_action "1/7:${action_color}
TAR is archiving the directory
${file_color}${dir}${action_color}
into
${file_color}${backup_file}"
# `tar --verify` for enhanced integrity
The man page says:
> -W, --verify: attempt to verify the archive after writing it
Just to note: I take it, this option is only usable when creating the archive, and not if later checking the integrity.
# `if`s can be completely pulled out of the whole script
More importantly, it makes the script more readable this way:
tar --create --file="${backup_file}" "$1" --totals --verify ||
print_error "TAR failed to archive the directory!"
# Too long lines of code could be split
There were also places where the code itself could be formatted in two lines simply with the already present `|` (pipe), which acts as delimiter too.
pv --progress --timer --eta --rate --average-rate --bytes "${backup_file}.xz" |
openssl enc -aes-256-cbc -md sha256 -salt -out "${backup_file}.xz.enc" -pass file:"$passwd_file" 2> /dev/null ||
print_error "OpenSSL failed to encrypt the compressed file!"
# Average rate could further be added to the `pv` statement
As shown above, this could be somewhat useful to me at least if the file is very large.
# Remove `-W` parameter from `pv`
The `--wait` parameter is useless in case like this, where we are not waiting for user input. What's more, it caused `pv` not to output anything on small files.
# As pointed out by Janos, remove the `sha512sum --check`
Not only it is useless in this case, but it takes a few seconds. Better yet, you could replace it with showing the SHA-512 hash sum like this:
awk '{ print $1 }' "${backup_file}.xz.enc.SHA512SUM"
# Use `cmp` with `--silent` parameter
As you are not interested in actual differences in those files, and only wish to check the return value of `cmp`, this is the right way:
cmp --silent "${backup_file}.xz" "${backup_file}.xz.dec" &&
echo "Files are identical." ||
print_error "Failed to compare files!"
# Re-write awkward texts
I have re-written most of them, but one example:
> Comparing your un-encrypted, compressed, archived, directory file
could sound better as
> CMP is comparing the un-encrypted compressed file
# Current code looks like this
#!/bin/sh
# Treat unset variables as an error when substituting
set -o nounset
[ "$#" -eq 0 ] && echo "You need to give me one directory!" && exit 1
[ "$#" -gt 1 ] && echo "Multiple arguments are not supported!" && exit 1
[ ! -d "$1" ] && echo "This is not a directory!" && exit 1
[ ! -w "$PWD" ] && echo "The current directory is not writable by you!" && exit 1
# In order to compress many directories with the same password,
# I decided to create a password file to avoid too many annoying prompts
passwd_file="/home/vlastimil/.blablablabla"
[ ! -f "$passwd_file" ] && echo "The password file does not exist!" && exit 1
dir=$(basename "$1")
today=$(date +%Y-%m-%d)
backup_dir="${dir}_${today}"
# backup_dir="${dir}"
backup_file="${backup_dir}.tar"
# TAR is archiving the directory into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}" ] && echo "File ${backup_file} exists, exiting." && exit 1
# XZ is compressing the archive into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}.xz" ] && echo "File ${backup_file}.xz exists, exiting." && exit 1
# OpenSSL is decrypting the file (for verification) into the following temporary file,
# it gets deleted on successful processing
[ -f "${backup_file}.xz.dec" ] && echo "File ${backup_file}.xz.dec exists, exiting." && exit 1
# OpenSSL is encrypting the compressed file into the following permanent file,
# this is the result of successful processing
[ -f "${backup_file}.xz.enc" ] && echo "File ${backup_file}.xz.enc exists, exiting." && exit 1
# SHA512SUM is computing a hash sum of the encrypted file into the following permanent file,
# this is the result of successful processing
[ -f "${backup_file}.xz.enc.SHA512SUM" ] && echo "File ${backup_file}.xz.enc.SHA512SUM exists, exiting." && exit 1
bold=$(tput bold)
no_color=$(tput sgr0)
red=$(tput setaf 1)
#blue=$(tput setaf 4)
#cyan=$(tput setaf 6)
green=$(tput setaf 2)
white=$(tput setaf 7)
yellow=$(tput setaf 3)
#magenta=$(tput setaf 5)
action_number_color="${bold}${red}"
action_color="${bold}${yellow}"
file_color="${bold}${white}"
success_color="${bold}${green}"
print_action()
{
echo
echo "${action_number_color}$1${no_color}"
echo
}
print_error()
{
echo
echo "$1"
exit 1
}
#------------------------------------------------------------------------------------------------------------------
print_action "1/7:${action_color}
TAR is archiving the directory
${file_color}${dir}${action_color}
into
${file_color}${backup_file}"
tar --create --file="${backup_file}" "$1" --totals --verify ||
print_error "TAR failed to archive the directory!"
#------------------------------------------------------------------------------------------------------------------
print_action "2/7:${action_color}
XZ is compressing the archive
${file_color}${backup_file}${action_color}
into
${file_color}${backup_file}.xz"
xz --format=xz --check=sha256 -9 --threads=8 --keep --verbose --extreme "${backup_file}" ||
print_error "XZ failed to compress the backup file!"
#------------------------------------------------------------------------------------------------------------------
print_action "3/7:${action_color}
OpenSSL is encrypting the compressed file
${file_color}${backup_file}.xz${action_color}
into
${file_color}${backup_file}.xz.enc"
pv --progress --timer --eta --rate --average-rate --bytes "${backup_file}.xz" |
openssl enc -aes-256-cbc -md sha256 -salt -out "${backup_file}.xz.enc" -pass file:"$passwd_file" 2> /dev/null ||
print_error "OpenSSL failed to encrypt the compressed file!"
#------------------------------------------------------------------------------------------------------------------
print_action "4/7:${action_color}
SHA512SUM is computing a hash sum of the encrypted file
${file_color}${backup_file}.xz.enc${action_color}
into
${file_color}${backup_file}.xz.enc.SHA512SUM"
sha512sum --binary "${backup_file}.xz.enc" > "${backup_file}.xz.enc.SHA512SUM" ||
print_error "SHA512SUM failed to compute the hash sum!"
#------------------------------------------------------------------------------------------------------------------
awk '{ print $1 }' "${backup_file}.xz.enc.SHA512SUM"
#------------------------------------------------------------------------------------------------------------------
print_action "5/7:${action_color}
OpenSSL is decrypting the file (for verification)
${file_color}${backup_file}.xz.enc${action_color}
into
${file_color}${backup_file}.xz.dec"
pv --progress --timer --eta --rate --average-rate --bytes "${backup_file}.xz.enc" |
openssl enc -aes-256-cbc -md sha256 -salt -out "${backup_file}.xz.dec" -d -pass file:"$passwd_file" 2> /dev/null ||
print_error "OpenSSL failed to decrypt the encrypted file!"
#------------------------------------------------------------------------------------------------------------------
print_action "6/7:${action_color}
CMP is comparing the un-encrypted compressed file
${file_color}${backup_file}.xz${action_color}
with
${file_color}${backup_file}.xz.dec"
cmp --silent "${backup_file}.xz" "${backup_file}.xz.dec" &&
echo "Files are identical." ||
print_error "Failed to compare files!" &&
{
print_action "7/7:${action_color}
Cleaning up"
rm "${backup_file}" &&
echo "${backup_file} removed"
rm "${backup_file}.xz" &&
echo "${backup_file}.xz removed"
rm "${backup_file}.xz.dec" &&
echo "${backup_file}.xz.dec removed"
echo
echo "${success_color}Your directory ${file_color}${dir}${success_color} has been successfully stored as ${file_color}${backup_file}.xz.enc${no_color}"
exit 0
}
# And how it appears in Cygwin
[![backupdir script output look in Cygwin][1]][1]
[1]: https://i.sstatic.net/UAPLb.png