How can I build a dynamic parameter list for mailx command in bash linux?

Question

OS: Red Hat Enterprise Linux Server release 5.11 (Tikanga)

I have a code sniplet:

!/usr/bin/env bash

v_mailx_parameter=""

v_cfg_email_adresse_to="john.doe_to@gmail.com"
v_cfg_email_subject="Report from December 2016"
v_tmp_email_text_name="Message Body"

v_email_main_file="appel orange.txt" # -> There is a SPACE in the file name! 
v_tmp_path="/home/server/tmp/"

if [ ! -z "${v_email_main_file}" ]
 then v_mailx_parameter="${v_mailx_parameter} -a \"${v_tmp_path}${v_email_main_file}\""
                                                 /\
                                                 ||
         Here is the problem but I need this because of spaces in the name
fi

echo -e "/bin/mailx ${v_mailx_parameter} -s \"${v_cfg_email_subject}\" \"${v_cfg_email_adresse_to}\""

cat ${v_tmp_email_text_name} | /bin/mailx ${v_mailx_parameter} -s "${v_cfg_email_subject}" "${v_cfg_email_adresse_to}"

exit

PROBLEM: I want to build up the parameters to the mailx command dynamically.

But I want to use the " double-quotes because there can be spaces in the file names.

Unfortunately the example above does not work... because the mailx takes the double-quotes as if they belong to the file name...and I get an error message.

I do not want to use the if else condition.. because I have many of files I need to send... I need a dynamic solution.

Maybe it is better to understand what my problem is:

It works in such a hardcoded way:

cat ${v_tmp_email_text_name} | /bin/mailx -a "/home/server/tmp/appel orange.txt" -s "${v_cfg_email_subject}" "${v_cfg_email_adresse_to}"

But so NOT:

v_mailx_parameter="-a \"${v_tmp_path}${v_email_main_file}\""

cat ${v_tmp_email_text_name} | /bin/mailx ${v_mailx_parameter} -s "${v_cfg_email_subject}" "${v_cfg_email_adresse_to}"

Thanks!

This is covered in detail in [BashFAQ #50](http://mywiki.wooledge.org/BashFAQ/050). — Charles Duffy, Jan 24 '17 at 16:16

Fred · Answer 1 · 2017-01-24T16:15:49.600

One easy way is to use an array.

declare -a parameters=()

parameters+=(-option1 OPTION VALUE)
parameters+=(-option2 "VALUE WITH SPACES")
parameters+=("/path/with spaces")
parameters+=("$PATH_WITH_SPACES")
if
  some_condition
then
  parameters+=(-optionA)
else
  parameters+=(-optionB)
fi
mailx "${parameters[@]}"

The "${parameters[@]}" expansion is special in that it ensure each of the element is separately quoted, without performing word splitting or expansion on the actual value of the elements (like when using "$@").

score 1 · Accepted Answer · answered Jan 24 '17 at 16:13

You need to use an array, which can hold all the arguments to easy logging and invocation. Note, though, that the input redirection to feed the message to mailx is not an argument.

#!/usr/bin/env bash

v_cfg_email_adresse_to="john.doe_to@gmail.com"
v_cfg_email_subject="Report from December 2016"
v_tmp_email_text_name="Message Body"

v_email_main_file="appel orange.txt"
v_tmp_path="/home/server/tmp/"

if [ ! -z "${v_email_main_file}" ]; then
  v_mailx_parameters+=( -a "${v_tmp_path}${v_email_main_file}" )
fi
v_mail_x_parameters+=( -s "${v_cfg_email_subject}" )
v_mail_x_parameters+=( "${v_cfg_email_adresse_to}" )

printf '/binmailx %s < %s\n' "${v_mail_x_parameters[*]}" "${v_tmp_email_text_name}"
/bin/mailx "${v_mailx_parameters[@]}" < "${v_tmp_email_text_name}"

How can I build a dynamic parameter list for mailx command in bash linux?

2 Answers2