Printing

Printing on Linux

Printing in Linux requires software that:

1. Converts your document from an application’s format into a language the printer understands
2. Sends the data to the right device (local USB, network, or remote)

The Linux standard for this is CUPS (Common UNIX Printing System).

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CUPS - Common UNIX Printing System

CUPS acts as a print server for both local and network printers. It uses a modular architecture to accommodate many different printer models and data formats - different printers may speak completely different page description languages, and CUPS handles the translation.

How CUPS Works

CUPS processes a print job through several components:

Component	Role
Scheduler	Manages print jobs, admin commands, printer status, data flow
Configuration files	cupsd.conf (system-wide settings), printers.conf (printer-specific)
Job files	Queued documents stored under /var/spool/cups; data files prefixed d, control files prefixed c
Log files	Stored in /var/log/cups; include access, error, and page records
Filters	Convert job file formats to the printer’s format
Printer drivers	Stored under /etc/cups/ppd/; describe printer capabilities
Backend	Locates and communicates with printer devices

When you print: the scheduler validates the job → creates job files according to config → logs activity → sends data through filter → driver → backend → printer.

Configuration Files

• cupsd.conf - system-wide settings: network access, printer advertisement on LAN, management features. Does not contain printer-specific details.
• printers.conf - auto-generated when printers are added. Should not be edited by hand.

Both live under /etc/cups/.

Starting and Managing CUPS

systemctl status cups
sudo systemctl start cups
sudo systemctl enable cups      # start at boot
sudo systemctl restart cups
sudo systemctl stop cups

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Printing from the CLI

CUPS provides two CLI printing interfaces - one from each major UNIX lineage:

Tool	Origin	Usage
lp	System V	Primary printing command
lpr	BSD	Alternative syntax

Both support printing text, PostScript, PDF, and images. lp is a front-end to lpr that passes input through.

lp filename                     # print to default printer
lp -d HP-LaserJet filename      # print to a specific printer
lp -n 3 filename                # print 3 copies
program | lp                    # print output of a program
echo "test page" | lp           # print a string
lpoptions -d printer-name       # set the default printer
lpoptions help                  # list supported options

Managing Print Jobs

lpq -a                          # show queue status across all printers
lpstat -p -d                    # list available printers + their status
lpstat -a                       # check all connected printers + job numbers
cancel job-id                   # cancel a specific print job
lpmove job-id newprinter        # move job to a different printer

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PostScript and PDF

What is PostScript?

PostScript is a standard page description language from Adobe. It:

• Is a pure text format interpreted by a PostScript-compatible printer
• Describes page appearance in terms of vectors and fonts - resolution-independent
• Embeds information about page layout, fonts, and graphics within the page data
• Can be used on any PostScript-compatible printer (all modern printers support it)

PDF (Portable Document Format) has largely superseded PostScript. PDFs are much smaller due to compression, and PDF support is built into most modern applications. However, PostScript is still encountered as an intermediate format in printing pipelines.

Converting Between PostScript and PDF

These converters come from two packages: ghostscript (ps2pdf, pdf2ps) and poppler (pstopdf, pdftops).

Command	Action
pdf2ps file.pdf	Convert PDF to PostScript (→ file.ps)
ps2pdf file.ps	Convert PostScript to PDF (→ file.pdf)
pstopdf input.ps output.pdf	Alternative (poppler)
pdftops input.pdf output.ps	Alternative (poppler)
convert input.ps output.pdf	ImageMagick converter
convert input.pdf output.ps	ImageMagick converter

enscript - Text to PostScript

enscript converts plain text files to PostScript:

enscript textfile.txt                        # print directly to default printer
enscript -p psfile.ps textfile.txt           # convert to PostScript file
enscript -2 -r -p psfile.ps textfile.txt     # 2-column landscape layout
enscript -n -p psfile.ps textfile.txt        # n-column (1-9) output

• -2 - two columns
• -r - rotate to landscape (width > height), reducing total pages
• -p - output to file (not printer)

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PDF Manipulation

Common PDF manipulation tasks:

• Merge or split PDF files
• Rotate pages
• Extract specific page ranges
• Encrypt or decrypt PDFs
• Add/update metadata
• Fill out PDF forms

Tools Overview

Tool	Status	Notes
qpdf	✅ Recommended	Widely available, full-featured
ghostscript (gs)	✅ Recommended	Widely available, excellent for scripting
pdftk	⚠️ Avoid	Depends on unmaintained libgcj; many distros dropped it
pdfmod	GUI	Simple graphical editor
pdfinfo	CLI	Extract metadata from PDFs
flpsed	GUI	Add data/fill fields in PostScript docs

qpdf

qpdf --empty --pages 1.pdf 2.pdf -- merged.pdf         # merge two PDFs
qpdf --empty --pages 1.pdf 1-2 -- pages.pdf            # extract pages 1-2
qpdf --rotate=+90:1 1.pdf rotated.pdf                  # rotate page 1 clockwise 90°
qpdf --rotate=+90:1-z 1.pdf all-rotated.pdf            # rotate all pages
qpdf --encrypt mypw mypw 128 -- public.pdf private.pdf # 128-bit encryption
qpdf --decrypt --password=mypw private.pdf decrypted.pdf  # decrypt

Ghostscript (gs)

# Merge multiple PDFs into one
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite \
   -sOutputFile=all.pdf file1.pdf file2.pdf file3.pdf

# Split: extract pages 10–20
gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH \
   -dFirstPage=10 -dLastPage=20 \
   -sOutputFile=split.pdf file.pdf

Additional PDF Tools

Tool	Use
pdfinfo file.pdf	Show PDF metadata (title, pages, creator, etc.)
pdfmod	GUI: reorder, rotate, remove pages; edit title/author/keywords
flpsed	GUI: fill forms or add annotations to PostScript documents