reword options for cipher passphrase

Use --cipher-pass (cli), cipher_pass (conf) and PGBK_CIPHER_PASS (env)
to give the passphase

README.md

@@ -144,7 +144,7 @@ All the files procuded by a run of pg_back can be encrypted using age
 (<https://age-encryption.org/> an easy to use tool that does authenticated
 encryption of files). To keep things simple, encryption is done using a
 passphrase. To encrypt files, use the `--encrypt` option along with the
-`--cipher-pass` option or `PGBK_PASSPHRASE` environment variable to specify the
+`--cipher-pass` option or `PGBK_CIPHER_PASS` environment variable to specify the
 passphrase. When `encrypt` is set to true in the configuration file, the
 `--no-encrypt` option allows to disable encryption on the command line. By
 default, unencrypted source files are removed when they are successfully

config.go

@@ -317,7 +317,7 @@ func parseCli(args []string) (options, []string, error) {
 		changed = append(changed, "with-templates")
 	}
 
-	// To override cipher = true from the config file on the command line,
+	// To override encrypt = true from the config file on the command line,
 	// have MergeCliAndConfigOptions() use the false value
 	if *NoEncrypt {
 		opts.Encrypt = false
@@ -462,7 +462,7 @@ func loadConfigurationFile(path string) (options, error) {
 	opts.PreHook = s.Key("pre_backup_hook").MustString("")
 	opts.PostHook = s.Key("post_backup_hook").MustString("")
 	opts.Encrypt = s.Key("encrypt").MustBool(false)
-	opts.CipherPassphrase = s.Key("cipher_passphrase").MustString("")
+	opts.CipherPassphrase = s.Key("cipher_pass").MustString("")
 	opts.EncryptKeepSrc = s.Key("encrypt_keep_source").MustBool(false)
 
 	opts.Upload = s.Key("upload").MustString("none")

main.go

@@ -161,7 +161,7 @@ func run() (retVal error) {
 	// Ensure a non-empty passphrase is set when asking for encryption
 	if (opts.Encrypt || opts.Decrypt) && len(opts.CipherPassphrase) == 0 {
 		// Fallback on the environment
-		opts.CipherPassphrase = os.Getenv("PGBK_PASSPHRASE")
+		opts.CipherPassphrase = os.Getenv("PGBK_CIPHER_PASS")
 
 		if len(opts.CipherPassphrase) == 0 {
 			return fmt.Errorf("cannot use an empty passphrase for encryption")

pg_back.conf

@@ -57,9 +57,9 @@ checksum_algorithm = none
 # Encrypt the files produced, including globals and configuration.
 encrypt = false
 
-# Passphrase to use for encryption and decryption. The PGBK_PASSPHRASE
+# Passphrase to use for encryption and decryption. The PGBK_CIPHER_PASS
 # environment variable can be used alternatively.
-cipher_passphrase =
+cipher_pass =
 
 # Keep orignal files after encrypting them.
 encrypt_keep_source = false