What does spool mean for printing?

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Mark wrote a comment for me

I don't know offhand how to make cups not spool, that is, how to make the lpr command only exit after the printer driver has run.

What does "spool" for printing mean?

Google says it is a verb meaning "send (data that is intended for printing or processing on a peripheral device) to an intermediate store." What is the intermediate store that printing spool represents, for example, when printing by lpr command

Mark seems to relate the meaning of spool with blocking. But I can't figure that out by looking at the definition given by Google.

Thanks.

printing cups lpr

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asked 46 mins ago

Tim

23.4k66229412

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up vote
1
down vote

favorite

Mark wrote a comment for me

I don't know offhand how to make cups not spool, that is, how to make the lpr command only exit after the printer driver has run.

What does "spool" for printing mean?

Google says it is a verb meaning "send (data that is intended for printing or processing on a peripheral device) to an intermediate store." What is the intermediate store that printing spool represents, for example, when printing by lpr command

Mark seems to relate the meaning of spool with blocking. But I can't figure that out by looking at the definition given by Google.

Thanks.

printing cups lpr

share|improve this question

asked 46 mins ago

Tim

23.4k66229412

add a comment | 

up vote
1
down vote

favorite

up vote
1
down vote

favorite

Mark wrote a comment for me

I don't know offhand how to make cups not spool, that is, how to make the lpr command only exit after the printer driver has run.

What does "spool" for printing mean?

Google says it is a verb meaning "send (data that is intended for printing or processing on a peripheral device) to an intermediate store." What is the intermediate store that printing spool represents, for example, when printing by lpr command

Mark seems to relate the meaning of spool with blocking. But I can't figure that out by looking at the definition given by Google.

Thanks.

printing cups lpr

share|improve this question

asked 46 mins ago

Tim

23.4k66229412

Mark wrote a comment for me

I don't know offhand how to make cups not spool, that is, how to make the lpr command only exit after the printer driver has run.

What does "spool" for printing mean?

Google says it is a verb meaning "send (data that is intended for printing or processing on a peripheral device) to an intermediate store." What is the intermediate store that printing spool represents, for example, when printing by lpr command

Mark seems to relate the meaning of spool with blocking. But I can't figure that out by looking at the definition given by Google.

Thanks.

printing cups lpr

printing cups lpr

share|improve this question

asked 46 mins ago

Tim

23.4k66229412

share|improve this question

asked 46 mins ago

Tim

23.4k66229412

share|improve this question

share|improve this question

asked 46 mins ago

Tim

23.4k66229412

asked 46 mins ago

Tim

23.4k66229412

asked 46 mins ago

Tim

23.4k66229412

23.4k66229412

add a comment | 

add a comment | 

3 Answers
3

active

oldest

votes

up vote
3
down vote

A print spool is effectively a buffer, managed per job, with a program (the spooler) responsible for receiving jobs from submitting programs and feeding them to one or more printers. The point of a spool is to handle communication between two systems with different speeds; it means programs can submit print jobs as fast as they want, and those jobs are dealt with as fast (or slowly) as printers can handle.

Networked printers provide their own spools, and print servers (CUPS, lpd etc.) also implement spools. Most print systems also handle access control, quotas, banners, print options etc. Spools are used in other contexts; for example, tape-based backup servers now spool backup data from networked hosts on a fast disk-based storage system, so that they can then feed modern tape drives at the tremendous speeds they need to avoid tape shoe-shine.

In the context of the comment, the relevance of a spool is that it decorrelates the print job submission from its fulfillment. Not spooling would mean that the submission would only complete with the print job, and thus your lpr command would only complete once the job completed. Removing the spool on your computer might not have the desired result though since the printer itself could spool too!

share|improve this answer

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. Is spool with the same meaning used for other tasks than printing?
  – Tim
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Yes, see my update.
  – Stephen Kitt
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
  – Tim
  30 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  No, it’s not called “spool”.
  – Stephen Kitt
  27 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
  – Tim
  24 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
1
down vote

First , let's begin with the meaning of the term "spooling": Printers have a limited amount of memory, often times much smaller than the size of a document that you are wanting to print. Printer spooling allows you to send large documents, or multiple documents, to a printer and not have to wait for it to finish printing before continuing on to your next task.

Now, under Unix there are two printing systems:

1- The BSD spooling system that uses lpd daemon to schedule the print jobs.
2- The SVR4 -spooling system that uses lpsched as the scheduler.

BSD spooling system can extend to large, heterogeneous networks allowing many computers to share printers. Under the this system, access to printers is controlled by lpd daemon and the lpr program. lpr is the only program on a BSD system that can queue files for printing. Other programs such as enscript, ditroff etc., do so by calling lpr.

lpr accepts data to be printed, puts it in a spooling directory, and notifies the lpd daemon. For each print job, lpr creates two files, a control file (cfxxx) and a data file (dfxxx) in the spool directory, xxx indicating a unique job-id. The control file contains the information for handling the print job, including the identity of the owner. The data file contains the actual data to be printed.

The lpd daemon checks the /etc/printcap file to identify the destination printer. If the destination printer is a local device, lpd makes sure a copy of the lpd daemon is running on that print queue. Otherwise lpd opens a connection to the remote host to which the printer is connected and transfers both the control and data file to it.

Print jobs are scheduled by lpd on a First-In, First-Out (FIFO) basis. However, the system administrator may use the lpc command to alter the priority of the jobs in the print queue.

SVR4 spooling system This system was not designed with network printing. It is also a little more complicated to set up. Under SVR4 spooling system, the lp command accepts the data to be printed, makes a copy of it in the spool directory associated with the destination. The destination consists of a printer name and an optional specification of a class to which the printer belongs. When the specified printer is busy the job is sent to another printer in the same class. The spool directory is normally /var/spool/lp/request/printer-name and the print file is given a unique name to identify both the job and the user.

Access to the printer is controlled by lpsched daemon. It picks up the jobs from the spool directory and sends them to appropriate destination when it becomes available. lpsched also keeps a log, usually in /usr/spool/lp/log. The log file would indicate any error in processing the print jobs, as well as the user-name,

More 1,2,3

share|improve this answer

edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  It’s nice to mention your sources...
  – Stephen Kitt
  37 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  I didn't finish yet ;-)
  – Goro
  37 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

In a nut shell, a spooler consists of:

• a background program


• a directory per printer


• a file per print job

In your case, the foreground program (lpr) sends its print jobs to cups, which stores it and then uses serial, parallel, USB, network, ... communication to actually start the printing process.

So that's why nowadays even when the printer runs out of paper you can still continue using your computer, whereas back when I was a kid on CP/M, the whole computer locked up until you added more paper...

Why is it called "spooling"?

Because in those times, large computers used tape to store these kind of files as disks were too expensive, so when you were working inside the data center, the first thing you would hear was the tapes starting to spin (="to spool") and only after a second or 3-4 the printer would start printing (if you were lucky). ;-)

share|improve this answer

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

add a comment | 

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
3
down vote

A print spool is effectively a buffer, managed per job, with a program (the spooler) responsible for receiving jobs from submitting programs and feeding them to one or more printers. The point of a spool is to handle communication between two systems with different speeds; it means programs can submit print jobs as fast as they want, and those jobs are dealt with as fast (or slowly) as printers can handle.

Networked printers provide their own spools, and print servers (CUPS, lpd etc.) also implement spools. Most print systems also handle access control, quotas, banners, print options etc. Spools are used in other contexts; for example, tape-based backup servers now spool backup data from networked hosts on a fast disk-based storage system, so that they can then feed modern tape drives at the tremendous speeds they need to avoid tape shoe-shine.

In the context of the comment, the relevance of a spool is that it decorrelates the print job submission from its fulfillment. Not spooling would mean that the submission would only complete with the print job, and thus your lpr command would only complete once the job completed. Removing the spool on your computer might not have the desired result though since the printer itself could spool too!

share|improve this answer

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. Is spool with the same meaning used for other tasks than printing?
  – Tim
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Yes, see my update.
  – Stephen Kitt
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
  – Tim
  30 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  No, it’s not called “spool”.
  – Stephen Kitt
  27 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
  – Tim
  24 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
3
down vote

A print spool is effectively a buffer, managed per job, with a program (the spooler) responsible for receiving jobs from submitting programs and feeding them to one or more printers. The point of a spool is to handle communication between two systems with different speeds; it means programs can submit print jobs as fast as they want, and those jobs are dealt with as fast (or slowly) as printers can handle.

Networked printers provide their own spools, and print servers (CUPS, lpd etc.) also implement spools. Most print systems also handle access control, quotas, banners, print options etc. Spools are used in other contexts; for example, tape-based backup servers now spool backup data from networked hosts on a fast disk-based storage system, so that they can then feed modern tape drives at the tremendous speeds they need to avoid tape shoe-shine.

In the context of the comment, the relevance of a spool is that it decorrelates the print job submission from its fulfillment. Not spooling would mean that the submission would only complete with the print job, and thus your lpr command would only complete once the job completed. Removing the spool on your computer might not have the desired result though since the printer itself could spool too!

share|improve this answer

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. Is spool with the same meaning used for other tasks than printing?
  – Tim
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Yes, see my update.
  – Stephen Kitt
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
  – Tim
  30 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  No, it’s not called “spool”.
  – Stephen Kitt
  27 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
  – Tim
  24 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
3
down vote

up vote
3
down vote

A print spool is effectively a buffer, managed per job, with a program (the spooler) responsible for receiving jobs from submitting programs and feeding them to one or more printers. The point of a spool is to handle communication between two systems with different speeds; it means programs can submit print jobs as fast as they want, and those jobs are dealt with as fast (or slowly) as printers can handle.

Networked printers provide their own spools, and print servers (CUPS, lpd etc.) also implement spools. Most print systems also handle access control, quotas, banners, print options etc. Spools are used in other contexts; for example, tape-based backup servers now spool backup data from networked hosts on a fast disk-based storage system, so that they can then feed modern tape drives at the tremendous speeds they need to avoid tape shoe-shine.

In the context of the comment, the relevance of a spool is that it decorrelates the print job submission from its fulfillment. Not spooling would mean that the submission would only complete with the print job, and thus your lpr command would only complete once the job completed. Removing the spool on your computer might not have the desired result though since the printer itself could spool too!

share|improve this answer

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

A print spool is effectively a buffer, managed per job, with a program (the spooler) responsible for receiving jobs from submitting programs and feeding them to one or more printers. The point of a spool is to handle communication between two systems with different speeds; it means programs can submit print jobs as fast as they want, and those jobs are dealt with as fast (or slowly) as printers can handle.

Networked printers provide their own spools, and print servers (CUPS, lpd etc.) also implement spools. Most print systems also handle access control, quotas, banners, print options etc. Spools are used in other contexts; for example, tape-based backup servers now spool backup data from networked hosts on a fast disk-based storage system, so that they can then feed modern tape drives at the tremendous speeds they need to avoid tape shoe-shine.

In the context of the comment, the relevance of a spool is that it decorrelates the print job submission from its fulfillment. Not spooling would mean that the submission would only complete with the print job, and thus your lpr command would only complete once the job completed. Removing the spool on your computer might not have the desired result though since the printer itself could spool too!

share|improve this answer

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

share|improve this answer

share|improve this answer

edited 28 mins ago

edited 28 mins ago

edited 28 mins ago

answered 35 mins ago

Stephen Kitt

146k22321387

answered 35 mins ago

Stephen Kitt

146k22321387

answered 35 mins ago

Stephen Kitt

146k22321387

146k22321387

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. Is spool with the same meaning used for other tasks than printing?
  – Tim
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Yes, see my update.
  – Stephen Kitt
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
  – Tim
  30 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  No, it’s not called “spool”.
  – Stephen Kitt
  27 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
  – Tim
  24 mins ago
  

  
  
  
  

 | 
show 2 more comments

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks. Is spool with the same meaning used for other tasks than printing?
  – Tim
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Yes, see my update.
  – Stephen Kitt
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
  – Tim
  30 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  No, it’s not called “spool”.
  – Stephen Kitt
  27 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
  – Tim
  24 mins ago
  

  
  
  
  

Thanks. Is spool with the same meaning used for other tasks than printing?
– Tim
31 mins ago

Thanks. Is spool with the same meaning used for other tasks than printing?
– Tim
31 mins ago

Yes, see my update.
– Stephen Kitt
31 mins ago

Yes, see my update.
– Stephen Kitt
31 mins ago

Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
– Tim
30 mins ago

Linux kernel has buffer for read() and write(). Is that buffer also called "spool"?
– Tim
30 mins ago

No, it’s not called “spool”.
– Stephen Kitt
27 mins ago

No, it’s not called “spool”.
– Stephen Kitt
27 mins ago

Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
– Tim
24 mins ago

Which part of the meaning of "spool" make it not applicable to the IO buffer of Linux kernel?
– Tim
24 mins ago

 | 
show 2 more comments

up vote
1
down vote

First , let's begin with the meaning of the term "spooling": Printers have a limited amount of memory, often times much smaller than the size of a document that you are wanting to print. Printer spooling allows you to send large documents, or multiple documents, to a printer and not have to wait for it to finish printing before continuing on to your next task.

Now, under Unix there are two printing systems:

1- The BSD spooling system that uses lpd daemon to schedule the print jobs.
2- The SVR4 -spooling system that uses lpsched as the scheduler.

BSD spooling system can extend to large, heterogeneous networks allowing many computers to share printers. Under the this system, access to printers is controlled by lpd daemon and the lpr program. lpr is the only program on a BSD system that can queue files for printing. Other programs such as enscript, ditroff etc., do so by calling lpr.

lpr accepts data to be printed, puts it in a spooling directory, and notifies the lpd daemon. For each print job, lpr creates two files, a control file (cfxxx) and a data file (dfxxx) in the spool directory, xxx indicating a unique job-id. The control file contains the information for handling the print job, including the identity of the owner. The data file contains the actual data to be printed.

The lpd daemon checks the /etc/printcap file to identify the destination printer. If the destination printer is a local device, lpd makes sure a copy of the lpd daemon is running on that print queue. Otherwise lpd opens a connection to the remote host to which the printer is connected and transfers both the control and data file to it.

Print jobs are scheduled by lpd on a First-In, First-Out (FIFO) basis. However, the system administrator may use the lpc command to alter the priority of the jobs in the print queue.

SVR4 spooling system This system was not designed with network printing. It is also a little more complicated to set up. Under SVR4 spooling system, the lp command accepts the data to be printed, makes a copy of it in the spool directory associated with the destination. The destination consists of a printer name and an optional specification of a class to which the printer belongs. When the specified printer is busy the job is sent to another printer in the same class. The spool directory is normally /var/spool/lp/request/printer-name and the print file is given a unique name to identify both the job and the user.

Access to the printer is controlled by lpsched daemon. It picks up the jobs from the spool directory and sends them to appropriate destination when it becomes available. lpsched also keeps a log, usually in /usr/spool/lp/log. The log file would indicate any error in processing the print jobs, as well as the user-name,

More 1,2,3

share|improve this answer

edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  It’s nice to mention your sources...
  – Stephen Kitt
  37 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  I didn't finish yet ;-)
  – Goro
  37 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

First , let's begin with the meaning of the term "spooling": Printers have a limited amount of memory, often times much smaller than the size of a document that you are wanting to print. Printer spooling allows you to send large documents, or multiple documents, to a printer and not have to wait for it to finish printing before continuing on to your next task.

Now, under Unix there are two printing systems:

1- The BSD spooling system that uses lpd daemon to schedule the print jobs.
2- The SVR4 -spooling system that uses lpsched as the scheduler.

BSD spooling system can extend to large, heterogeneous networks allowing many computers to share printers. Under the this system, access to printers is controlled by lpd daemon and the lpr program. lpr is the only program on a BSD system that can queue files for printing. Other programs such as enscript, ditroff etc., do so by calling lpr.

lpr accepts data to be printed, puts it in a spooling directory, and notifies the lpd daemon. For each print job, lpr creates two files, a control file (cfxxx) and a data file (dfxxx) in the spool directory, xxx indicating a unique job-id. The control file contains the information for handling the print job, including the identity of the owner. The data file contains the actual data to be printed.

The lpd daemon checks the /etc/printcap file to identify the destination printer. If the destination printer is a local device, lpd makes sure a copy of the lpd daemon is running on that print queue. Otherwise lpd opens a connection to the remote host to which the printer is connected and transfers both the control and data file to it.

Print jobs are scheduled by lpd on a First-In, First-Out (FIFO) basis. However, the system administrator may use the lpc command to alter the priority of the jobs in the print queue.

SVR4 spooling system This system was not designed with network printing. It is also a little more complicated to set up. Under SVR4 spooling system, the lp command accepts the data to be printed, makes a copy of it in the spool directory associated with the destination. The destination consists of a printer name and an optional specification of a class to which the printer belongs. When the specified printer is busy the job is sent to another printer in the same class. The spool directory is normally /var/spool/lp/request/printer-name and the print file is given a unique name to identify both the job and the user.

Access to the printer is controlled by lpsched daemon. It picks up the jobs from the spool directory and sends them to appropriate destination when it becomes available. lpsched also keeps a log, usually in /usr/spool/lp/log. The log file would indicate any error in processing the print jobs, as well as the user-name,

More 1,2,3

share|improve this answer

edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  It’s nice to mention your sources...
  – Stephen Kitt
  37 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  I didn't finish yet ;-)
  – Goro
  37 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

up vote
1
down vote

First , let's begin with the meaning of the term "spooling": Printers have a limited amount of memory, often times much smaller than the size of a document that you are wanting to print. Printer spooling allows you to send large documents, or multiple documents, to a printer and not have to wait for it to finish printing before continuing on to your next task.

Now, under Unix there are two printing systems:

1- The BSD spooling system that uses lpd daemon to schedule the print jobs.
2- The SVR4 -spooling system that uses lpsched as the scheduler.

BSD spooling system can extend to large, heterogeneous networks allowing many computers to share printers. Under the this system, access to printers is controlled by lpd daemon and the lpr program. lpr is the only program on a BSD system that can queue files for printing. Other programs such as enscript, ditroff etc., do so by calling lpr.

lpr accepts data to be printed, puts it in a spooling directory, and notifies the lpd daemon. For each print job, lpr creates two files, a control file (cfxxx) and a data file (dfxxx) in the spool directory, xxx indicating a unique job-id. The control file contains the information for handling the print job, including the identity of the owner. The data file contains the actual data to be printed.

The lpd daemon checks the /etc/printcap file to identify the destination printer. If the destination printer is a local device, lpd makes sure a copy of the lpd daemon is running on that print queue. Otherwise lpd opens a connection to the remote host to which the printer is connected and transfers both the control and data file to it.

Print jobs are scheduled by lpd on a First-In, First-Out (FIFO) basis. However, the system administrator may use the lpc command to alter the priority of the jobs in the print queue.

SVR4 spooling system This system was not designed with network printing. It is also a little more complicated to set up. Under SVR4 spooling system, the lp command accepts the data to be printed, makes a copy of it in the spool directory associated with the destination. The destination consists of a printer name and an optional specification of a class to which the printer belongs. When the specified printer is busy the job is sent to another printer in the same class. The spool directory is normally /var/spool/lp/request/printer-name and the print file is given a unique name to identify both the job and the user.

Access to the printer is controlled by lpsched daemon. It picks up the jobs from the spool directory and sends them to appropriate destination when it becomes available. lpsched also keeps a log, usually in /usr/spool/lp/log. The log file would indicate any error in processing the print jobs, as well as the user-name,

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edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

First , let's begin with the meaning of the term "spooling": Printers have a limited amount of memory, often times much smaller than the size of a document that you are wanting to print. Printer spooling allows you to send large documents, or multiple documents, to a printer and not have to wait for it to finish printing before continuing on to your next task.

Now, under Unix there are two printing systems:

1- The BSD spooling system that uses lpd daemon to schedule the print jobs.
2- The SVR4 -spooling system that uses lpsched as the scheduler.

BSD spooling system can extend to large, heterogeneous networks allowing many computers to share printers. Under the this system, access to printers is controlled by lpd daemon and the lpr program. lpr is the only program on a BSD system that can queue files for printing. Other programs such as enscript, ditroff etc., do so by calling lpr.

lpr accepts data to be printed, puts it in a spooling directory, and notifies the lpd daemon. For each print job, lpr creates two files, a control file (cfxxx) and a data file (dfxxx) in the spool directory, xxx indicating a unique job-id. The control file contains the information for handling the print job, including the identity of the owner. The data file contains the actual data to be printed.

The lpd daemon checks the /etc/printcap file to identify the destination printer. If the destination printer is a local device, lpd makes sure a copy of the lpd daemon is running on that print queue. Otherwise lpd opens a connection to the remote host to which the printer is connected and transfers both the control and data file to it.

Print jobs are scheduled by lpd on a First-In, First-Out (FIFO) basis. However, the system administrator may use the lpc command to alter the priority of the jobs in the print queue.

SVR4 spooling system This system was not designed with network printing. It is also a little more complicated to set up. Under SVR4 spooling system, the lp command accepts the data to be printed, makes a copy of it in the spool directory associated with the destination. The destination consists of a printer name and an optional specification of a class to which the printer belongs. When the specified printer is busy the job is sent to another printer in the same class. The spool directory is normally /var/spool/lp/request/printer-name and the print file is given a unique name to identify both the job and the user.

Access to the printer is controlled by lpsched daemon. It picks up the jobs from the spool directory and sends them to appropriate destination when it becomes available. lpsched also keeps a log, usually in /usr/spool/lp/log. The log file would indicate any error in processing the print jobs, as well as the user-name,

More 1,2,3

share|improve this answer

edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

share|improve this answer

share|improve this answer

edited 24 mins ago

edited 24 mins ago

edited 24 mins ago

answered 38 mins ago

Goro

4,18552255

answered 38 mins ago

Goro

4,18552255

answered 38 mins ago

Goro

4,18552255

4,18552255

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  It’s nice to mention your sources...
  – Stephen Kitt
  37 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  I didn't finish yet ;-)
  – Goro
  37 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  It’s nice to mention your sources...
  – Stephen Kitt
  37 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  I didn't finish yet ;-)
  – Goro
  37 mins ago
  

  
  
  
  

1

1

It’s nice to mention your sources...
– Stephen Kitt
37 mins ago

It’s nice to mention your sources...
– Stephen Kitt
37 mins ago

I didn't finish yet ;-)
– Goro
37 mins ago

I didn't finish yet ;-)
– Goro
37 mins ago

add a comment | 

up vote
1
down vote

In a nut shell, a spooler consists of:

• a background program


• a directory per printer


• a file per print job

In your case, the foreground program (lpr) sends its print jobs to cups, which stores it and then uses serial, parallel, USB, network, ... communication to actually start the printing process.

So that's why nowadays even when the printer runs out of paper you can still continue using your computer, whereas back when I was a kid on CP/M, the whole computer locked up until you added more paper...

Why is it called "spooling"?

Because in those times, large computers used tape to store these kind of files as disks were too expensive, so when you were working inside the data center, the first thing you would hear was the tapes starting to spin (="to spool") and only after a second or 3-4 the printer would start printing (if you were lucky). ;-)

share|improve this answer

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

add a comment | 

up vote
1
down vote

In a nut shell, a spooler consists of:

• a background program


• a directory per printer


• a file per print job

In your case, the foreground program (lpr) sends its print jobs to cups, which stores it and then uses serial, parallel, USB, network, ... communication to actually start the printing process.

So that's why nowadays even when the printer runs out of paper you can still continue using your computer, whereas back when I was a kid on CP/M, the whole computer locked up until you added more paper...

Why is it called "spooling"?

Because in those times, large computers used tape to store these kind of files as disks were too expensive, so when you were working inside the data center, the first thing you would hear was the tapes starting to spin (="to spool") and only after a second or 3-4 the printer would start printing (if you were lucky). ;-)

share|improve this answer

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

add a comment | 

up vote
1
down vote

up vote
1
down vote

In a nut shell, a spooler consists of:

• a background program


• a directory per printer


• a file per print job

In your case, the foreground program (lpr) sends its print jobs to cups, which stores it and then uses serial, parallel, USB, network, ... communication to actually start the printing process.

So that's why nowadays even when the printer runs out of paper you can still continue using your computer, whereas back when I was a kid on CP/M, the whole computer locked up until you added more paper...

Why is it called "spooling"?

Because in those times, large computers used tape to store these kind of files as disks were too expensive, so when you were working inside the data center, the first thing you would hear was the tapes starting to spin (="to spool") and only after a second or 3-4 the printer would start printing (if you were lucky). ;-)

share|improve this answer

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

In a nut shell, a spooler consists of:

• a background program


• a directory per printer


• a file per print job

In your case, the foreground program (lpr) sends its print jobs to cups, which stores it and then uses serial, parallel, USB, network, ... communication to actually start the printing process.

So that's why nowadays even when the printer runs out of paper you can still continue using your computer, whereas back when I was a kid on CP/M, the whole computer locked up until you added more paper...

Why is it called "spooling"?

Because in those times, large computers used tape to store these kind of files as disks were too expensive, so when you were working inside the data center, the first thing you would hear was the tapes starting to spin (="to spool") and only after a second or 3-4 the printer would start printing (if you were lucky). ;-)

share|improve this answer

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

share|improve this answer

share|improve this answer

edited 11 mins ago

edited 11 mins ago

edited 11 mins ago

answered 17 mins ago

Fabby

2,188621

answered 17 mins ago

Fabby

2,188621

answered 17 mins ago

Fabby

2,188621

2,188621

add a comment | 

add a comment | 

 

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