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Why does cron require MTA for logging?
2019 Community Moderator Electioncron logging but not working on some commandsHow can I disable UFW logging for a specific event?Why does this command work for logging script output?Is any extended logging available for cron jobs?Skip syslog/rsyslog logging of certain cron jobsCentOS 6 Cron Logging Without PostfixCron stopped logging to /var/log/cron.logWhy oracle linux system's /var/log/cron timezone different from system date?Why has cron stopped processing commands?Debian: Disable logging SSH sessions for an user
Why does cron require MTA for logging? Is there any particular advantage to this? Why can't it create a log file like most other utilities?
networking cron logs email
edited Mar 10 at 19:39
Glorfindel
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
add a comment |
Why does cron require MTA for logging? Is there any particular advantage to this? Why can't it create a log file like most other utilities?
networking cron logs email
edited Mar 10 at 19:39
Glorfindel
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago
add a comment |
Why does cron require MTA for logging? Is there any particular advantage to this? Why can't it create a log file like most other utilities?
networking cron logs email
edited Mar 10 at 19:39
Glorfindel
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
Why does cron require MTA for logging? Is there any particular advantage to this? Why can't it create a log file like most other utilities?
networking cron logs email
networking cron logs email
edited Mar 10 at 19:39
Glorfindel
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
edited Mar 10 at 19:39
Glorfindel
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
edited Mar 10 at 19:39
Glorfindel
3051411
edited Mar 10 at 19:39
Glorfindel
3051411
edited Mar 10 at 19:39
Glorfindel
3051411
3051411
asked Mar 10 at 11:31
NikhilNikhil
367114
asked Mar 10 at 11:31
NikhilNikhil
367114
asked Mar 10 at 11:31
NikhilNikhil
367114
367114
Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago
add a comment |
Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago
Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago
Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago
add a comment |
2 Answers
2
active
oldest
votes
Consider that the traditional "standard" way of logging data is syslog, where the metadata included in the messages are the "facility code" and the priority level. The facility code can be used to separate log streams from different services so that they can be split into different log files, etc. (even though the facility codes are somewhat limited in that they have fixed traditional meanings.)
What syslog doesn't have, is a way to separate messages for or from different users, and that's something that cron needs on a traditional multi-user system. It's no use collecting the messages from all users' cron jobs to a common log file where only the system administrator can see them. On the other hand, email naturally provides for sending messages to different users, so it's a logical choice here. The alternative would be for cron to do the work manually, and to create logfiles to each users' home directory, but a traditional multi-user Unix system would be assumed to have a working MTA, so implementing it in cron would have been mostly a futile exercise.
On modern systems, there might be alternative choices, of course.
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
add a comment |
I assume that by "logging" you mean storing the actual output of jobs. The running of jobs is already logged in the cron log in /var/cron/log (the path may differ between systems). There is no MTA required for this log.
A cron job is run as the user whose crontab the job is part of.
In the general case, there is no guarantee that this user is able to create files on the system (a user may not be an interactive user), especially not under the /var hierarchy where logs are usually created. The safest way to notify the user of errors and other output from a job is therefore to collect these and send them by email to the user. This would also allow the user to set up email redirection for the account to be able to see e.g. errors in their preferred location.
If the user wants to save the output of a job to file, they may do so with a simple redirection in the crontab:
0 */2 * * * "$HOME/scripts/myscript" >"$HOME/logs/myscript.log" 2>&1
This would run "$HOME/scripts/myscript" every second hour, on the hour, and would save all output to "$HOME/logs/myscript.log". No emails would be created by running this job as all output is redirected. Without the 2>&1, error messages would still be sent by email.
This allows the user to choose where the output goes.
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
add a comment |
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2 Answers
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2 Answers
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Consider that the traditional "standard" way of logging data is syslog, where the metadata included in the messages are the "facility code" and the priority level. The facility code can be used to separate log streams from different services so that they can be split into different log files, etc. (even though the facility codes are somewhat limited in that they have fixed traditional meanings.)
What syslog doesn't have, is a way to separate messages for or from different users, and that's something that cron needs on a traditional multi-user system. It's no use collecting the messages from all users' cron jobs to a common log file where only the system administrator can see them. On the other hand, email naturally provides for sending messages to different users, so it's a logical choice here. The alternative would be for cron to do the work manually, and to create logfiles to each users' home directory, but a traditional multi-user Unix system would be assumed to have a working MTA, so implementing it in cron would have been mostly a futile exercise.
On modern systems, there might be alternative choices, of course.
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
add a comment |
Consider that the traditional "standard" way of logging data is syslog, where the metadata included in the messages are the "facility code" and the priority level. The facility code can be used to separate log streams from different services so that they can be split into different log files, etc. (even though the facility codes are somewhat limited in that they have fixed traditional meanings.)
What syslog doesn't have, is a way to separate messages for or from different users, and that's something that cron needs on a traditional multi-user system. It's no use collecting the messages from all users' cron jobs to a common log file where only the system administrator can see them. On the other hand, email naturally provides for sending messages to different users, so it's a logical choice here. The alternative would be for cron to do the work manually, and to create logfiles to each users' home directory, but a traditional multi-user Unix system would be assumed to have a working MTA, so implementing it in cron would have been mostly a futile exercise.
On modern systems, there might be alternative choices, of course.
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
add a comment |
Consider that the traditional "standard" way of logging data is syslog, where the metadata included in the messages are the "facility code" and the priority level. The facility code can be used to separate log streams from different services so that they can be split into different log files, etc. (even though the facility codes are somewhat limited in that they have fixed traditional meanings.)
What syslog doesn't have, is a way to separate messages for or from different users, and that's something that cron needs on a traditional multi-user system. It's no use collecting the messages from all users' cron jobs to a common log file where only the system administrator can see them. On the other hand, email naturally provides for sending messages to different users, so it's a logical choice here. The alternative would be for cron to do the work manually, and to create logfiles to each users' home directory, but a traditional multi-user Unix system would be assumed to have a working MTA, so implementing it in cron would have been mostly a futile exercise.
On modern systems, there might be alternative choices, of course.
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
Consider that the traditional "standard" way of logging data is syslog, where the metadata included in the messages are the "facility code" and the priority level. The facility code can be used to separate log streams from different services so that they can be split into different log files, etc. (even though the facility codes are somewhat limited in that they have fixed traditional meanings.)
What syslog doesn't have, is a way to separate messages for or from different users, and that's something that cron needs on a traditional multi-user system. It's no use collecting the messages from all users' cron jobs to a common log file where only the system administrator can see them. On the other hand, email naturally provides for sending messages to different users, so it's a logical choice here. The alternative would be for cron to do the work manually, and to create logfiles to each users' home directory, but a traditional multi-user Unix system would be assumed to have a working MTA, so implementing it in cron would have been mostly a futile exercise.
On modern systems, there might be alternative choices, of course.
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
answered Mar 10 at 12:02
ilkkachuilkkachu
61.2k1099175
61.2k1099175
add a comment |
add a comment |
I assume that by "logging" you mean storing the actual output of jobs. The running of jobs is already logged in the cron log in /var/cron/log (the path may differ between systems). There is no MTA required for this log.
A cron job is run as the user whose crontab the job is part of.
In the general case, there is no guarantee that this user is able to create files on the system (a user may not be an interactive user), especially not under the /var hierarchy where logs are usually created. The safest way to notify the user of errors and other output from a job is therefore to collect these and send them by email to the user. This would also allow the user to set up email redirection for the account to be able to see e.g. errors in their preferred location.
If the user wants to save the output of a job to file, they may do so with a simple redirection in the crontab:
0 */2 * * * "$HOME/scripts/myscript" >"$HOME/logs/myscript.log" 2>&1
This would run "$HOME/scripts/myscript" every second hour, on the hour, and would save all output to "$HOME/logs/myscript.log". No emails would be created by running this job as all output is redirected. Without the 2>&1, error messages would still be sent by email.
This allows the user to choose where the output goes.
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
add a comment |
I assume that by "logging" you mean storing the actual output of jobs. The running of jobs is already logged in the cron log in /var/cron/log (the path may differ between systems). There is no MTA required for this log.
A cron job is run as the user whose crontab the job is part of.
In the general case, there is no guarantee that this user is able to create files on the system (a user may not be an interactive user), especially not under the /var hierarchy where logs are usually created. The safest way to notify the user of errors and other output from a job is therefore to collect these and send them by email to the user. This would also allow the user to set up email redirection for the account to be able to see e.g. errors in their preferred location.
If the user wants to save the output of a job to file, they may do so with a simple redirection in the crontab:
0 */2 * * * "$HOME/scripts/myscript" >"$HOME/logs/myscript.log" 2>&1
This would run "$HOME/scripts/myscript" every second hour, on the hour, and would save all output to "$HOME/logs/myscript.log". No emails would be created by running this job as all output is redirected. Without the 2>&1, error messages would still be sent by email.
This allows the user to choose where the output goes.
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
add a comment |
I assume that by "logging" you mean storing the actual output of jobs. The running of jobs is already logged in the cron log in /var/cron/log (the path may differ between systems). There is no MTA required for this log.
A cron job is run as the user whose crontab the job is part of.
In the general case, there is no guarantee that this user is able to create files on the system (a user may not be an interactive user), especially not under the /var hierarchy where logs are usually created. The safest way to notify the user of errors and other output from a job is therefore to collect these and send them by email to the user. This would also allow the user to set up email redirection for the account to be able to see e.g. errors in their preferred location.
If the user wants to save the output of a job to file, they may do so with a simple redirection in the crontab:
0 */2 * * * "$HOME/scripts/myscript" >"$HOME/logs/myscript.log" 2>&1
This would run "$HOME/scripts/myscript" every second hour, on the hour, and would save all output to "$HOME/logs/myscript.log". No emails would be created by running this job as all output is redirected. Without the 2>&1, error messages would still be sent by email.
This allows the user to choose where the output goes.
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
I assume that by "logging" you mean storing the actual output of jobs. The running of jobs is already logged in the cron log in /var/cron/log (the path may differ between systems). There is no MTA required for this log.
A cron job is run as the user whose crontab the job is part of.
In the general case, there is no guarantee that this user is able to create files on the system (a user may not be an interactive user), especially not under the /var hierarchy where logs are usually created. The safest way to notify the user of errors and other output from a job is therefore to collect these and send them by email to the user. This would also allow the user to set up email redirection for the account to be able to see e.g. errors in their preferred location.
If the user wants to save the output of a job to file, they may do so with a simple redirection in the crontab:
0 */2 * * * "$HOME/scripts/myscript" >"$HOME/logs/myscript.log" 2>&1
This would run "$HOME/scripts/myscript" every second hour, on the hour, and would save all output to "$HOME/logs/myscript.log". No emails would be created by running this job as all output is redirected. Without the 2>&1, error messages would still be sent by email.
This allows the user to choose where the output goes.
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
edited Mar 10 at 12:38
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
answered Mar 10 at 11:55
KusalanandaKusalananda
135k17255422
135k17255422
add a comment |
add a comment |
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Bit of a nitpick, but I'm pretty sure cron doesn't need a MTA; unless you're shipping cron mails off to a different host, all it would need is a MDA (mail delivery agent).
– a CVn
2 days ago