# slocal(1) - man - phpman [SLOCAL(1mh)](https://www.chedong.com/phpMan.php/man/SLOCAL/1mh/markdown) [SLOCAL(1mh)](https://www.chedong.com/phpMan.php/man/SLOCAL/1mh/markdown) ## NAME slocal - asynchronously filter and deliver new mail to nmh ## SYNOPSIS **/usr/lib/mh/slocal** [**-help**] [**-version**] [**-addr** _address_] [**-info** _data_] [**-sender** _sender_] [**-user** _username_] [**-mailbox** _mbox_] [**-file** _file_] [**-maildelivery** _deliveryfile_] [**-verbose** | **-nover**‐‐ **bose**] [**-suppressdup** | **-nosuppressdup**] [**-debug**] ## DESCRIPTION **slocal** is a program designed to allow you to have your inbound mail processed according to a complex set of selection criteria. You do not normally invoke **slocal** yourself, rather **slocal** is invoked on your behalf by your system's Message Transfer Agent (such as **sendmail**) when the message arrives. The message selection criteria used by **slocal** is specified in the file “_.maildelivery_” in the user's home directory. You can specify an alternate file with the **-maildelivery** _file_ option. The syntax of this file is specified below. The message delivery address and message sender are determined from the Message Transfer Agent envelope information, if possible. Under **sendmail**, the sender will obtained from the UUCP “From:” line, if present. The user may override these values with the **-addr** and **-sender** switches. The message is normally read from the standard input. The **-file** switch sets the name of the file from which the message should be read, instead of reading stdin. This is useful when debugging a “_.maildelivery_” file. The **-user** switch tells **slocal** the name of the user for whom it is delivering mail. It must exist on the local system. The **-mailbox** switch tells **slocal** the name of the user's mail drop file. **slocal** is able to detect and suppress duplicate messages. To enable this, use the option ### -suppressdup in order to detect duplicates. Depending on your configuration, this database will be in ei‐ ther ndbm or Berkeley db format. The **-info** switch may be used to pass an arbitrary argument to sub-processes which **slocal** may invoke on your behalf. The **-verbose** switch causes **slocal** to give information on stdout about its progress. The **-de**‐‐ **bug** switch produces more verbose debugging output on stderr. These flags are useful when creating and debugging your “_.maildelivery_” file, as they allow you to see the decisions and actions that **slocal** is taking, as well as check for syntax errors in your “_.maildelivery_” file. ### Message Transfer Agents Most modern MTAs including **sendmail**, **postfix** and **exim** support a .forward file for directing incoming mail. You should include the line “| /usr/lib/mh/slocal -user username” in your .forward file in your home directory. This will cause your MTA to invoke **slocal** on your behalf when a message arrives. ### The Maildelivery File The “_.maildelivery_” file controls how **slocal** filters and delivers incoming mail. Each line of this file consists of five fields, separated by whitespace or comma. Since double-quotes are honored, these characters may be included in a single argument by enclosing the entire argument in double-quotes. A double-quote can be included by preceding it with a backslash. Lines beginning with `#' and blank lines are ignored. The format of each line in the “_.maildelivery_” file is: **header** **pattern** **action** **result** **string** **header**: The name of a header field (such as To, Cc, or From) that is to be searched for a pat‐ tern. This is any field in the headers of the message that might be present. The following special fields are also defined: _source_ the out-of-band sender information _addr_ the address that was used to cause delivery to the recipient _default_ this matches _only_ if the message hasn't been delivered yet _*_ this always matches **pattern**: The sequence of characters to match in the specified header field. Matching is case-in‐ sensitive, but does not use regular expressions. **action**: The action to take to deliver the message. When a message is delivered, a “Deliv‐ ery-Date: date” header is added which indicates the date and time that message was de‐ livered. _destroy_ This action always succeeds. _file_, _mbox_, or _>_ Append the message to the file named by _string_. The message is appended to the file in mbox (uucp) format. This is the format used by most other mail clients (such as mailx, elm). If the message can be appended to the file, then this action succeeds. _mmdf_ Identical to _file_, but always appends the message using the MMDF mailbox format. _pipe_ or _|_ Pipe the message as the standard input to the command named by _string_, using the Bourne shell **sh** to interpret the string. Prior to giving the string to the shell, it is expanded with the following built-in variables: $(sender) the out-of-band sender information $(address) the address that was used to cause delivery to the recipient $(size) the size of the message in bytes $(reply-to) either the “Reply-To:” or “From:” field of the message $(info) the out-of-band information specified _qpipe_ or _^_ Similar to _pipe_, but executes the command directly, after built-in variable expan‐ sion, without assistance from the shell. This action can be used to avoid quoting special characters which your shell might interpret. _folder_ or _+_ Store the message in the **nmh** folder named by _string_. Currently this is handled by piping the message to the **nmh** program **rcvstore**, although this may change in the fu‐ ture. **result**: Indicates how the action should be performed: _A_ Perform the action. If the action succeeds, then the message is considered deliv‐ ered. _R_ Perform the action. Regardless of the outcome of the action, the message is not considered delivered. _?_ Perform the action only if the message has not been delivered. If the action suc‐ ceeds, then the message is considered delivered. _N_ Perform the action only if the message has not been delivered and the previous ac‐ tion succeeded. If this action succeeds, then the message is considered delivered. The delivery file is always read completely, so that several matches can be made and several actions can be taken. ### Security of Delivery Files In order to prevent security problems, the “_.maildelivery_” file must be owned either by the user or by root, and must be writable only by the owner. If this is not the case, the file is not read. If the “_.maildelivery_” file cannot be found, or does not perform an action which delivers the message, then **slocal** will check for a global delivery file at _/etc/nmh/maildelivery_. This file is read according to the same rules. This file must be owned by root and must be writable only by root. If a global delivery file cannot be found or does not perform an action which delivers the message, then standard delivery to the user's mail drop is performed. ### Example Delivery File To summarize, here's an example delivery file: # # .maildelivery file for nmh's slocal # # Blank lines and lines beginning with a '#' are ignored # # FIELD PATTERN ACTION RESULT STRING # # File mail with foobar in the “To:” line into file foobar.log To foobar file A foobar.log # Pipe messages from coleman to the program message-archive From coleman pipe A /bin/message-archive # Anything to the “nmh-workers” mailing list is put in # its own folder, if not filed already To nmh-workers folder ? nmh-workers # Anything with Unix in the subject is put into # the file unix-mail Subject unix file A unix-mail # I don't want to read mail from Steve, so destroy it From steve destroy A - # Put anything not matched yet into mailbox default - file ? mailbox # always run rcvtty * - pipe R /usr/lib/mh/rcvtty ### Sub-process environment When a process is invoked, its environment is: the user/group-ids are set to recipient's ids; the working directory is the recipient's home directory; the umask is 0077; the process has no /dev/tty; the standard input is set to the message; the standard output and diagnostic output are set to /dev/null; all other file-descriptors are closed; the environment variables **$USER**, **$HOME**, **$SHELL** are set appropriately, and no other environment variables exist. The process is given a certain amount of time to execute. If the process does not exit within this limit, the process will be terminated with extreme prejudice. The amount of time is calculated as ((size / 60) + 300) seconds, where size is the number of bytes in the mes‐ sage (with 30 minutes the maximum time allowed). The exit status of the process is consulted in determining the success of the action. An exit status of zero means that the action succeeded. Any other exit status (or abnormal ter‐ mination) means that the action failed. In order to avoid any time limitations, you might implement a process that began by _fork_()-ing. The parent would return the appropriate value immediately, and the child could continue on, doing whatever it wanted for as long as it wanted. This approach is somewhat risky if the parent is going to return an exit status of zero. If the parent is going to re‐ turn a non-zero exit status, then this approach can lead to quicker delivery into your mail drop. ## FILES /etc/nmh/mts.conf nmh mts configuration file $HOME/.maildelivery The file controlling local delivery /etc/nmh/maildelivery Rather than the standard file /var/mail/$USER The default mail drop ## SEE ALSO [_rcvdist_(1)](https://www.chedong.com/phpMan.php/man/rcvdist/1/markdown), [_rcvpack_(1)](https://www.chedong.com/phpMan.php/man/rcvpack/1/markdown), [_rcvstore_(1)](https://www.chedong.com/phpMan.php/man/rcvstore/1/markdown), [_rcvtty_(1)](https://www.chedong.com/phpMan.php/man/rcvtty/1/markdown), [_mh-format_(5)](https://www.chedong.com/phpMan.php/man/mh-format/5/markdown) ## DEFAULTS `**-noverbose**' `**-nosuppressdup**' `**-maildelivery**' defaults to $HOME/.maildelivery `**-mailbox**' defaults to /var/mail/$USER `**-file**' defaults to stdin `**-addr**' defaults to the current user `**-user**' defaults to the current user ### -addr -user ## CONTEXT None ## HISTORY **slocal** was originally designed to be backward-compatible with the **maildelivery** facility pro‐ vided by **MMDF-II**. Thus, the “_.maildelivery_” file syntax is somewhat limited. But **slocal** has been modified and extended, so that is it no longer compatible with **MMDF-II**. In addition to an exit status of zero, the **MMDF** values **RP**___**MOK** (32) and **RP**___**OK** (9) mean that the message has been fully delivered. Any other non-zero exit status, including abnormal termination, is interpreted as the **MMDF** value **RP**___**MECH** (200), which means “use an alternate route” (deliver the message to the mail drop). ## BUGS Only two return codes are meaningful, others should be. **slocal** was originally designed to be backwards-compatible with the **maildelivery** functionality provided by **MMDF-II**. nmh-1.7.1 2016-05-02 [SLOCAL(1mh)](https://www.chedong.com/phpMan.php/man/SLOCAL/1mh/markdown)