Linux CLI 49 🐧 pr and printf commands - KandZ

cat file1.txt file2.txt
pr -m -l 10 file1.txt file2.txt
pr -3 -l 10 file1.txt

printf "My favorite number is %d and my favorite letter is %c.\n" 42 'A'
printf "Pi is approximately %.2f\n" 3.14159
printf "%b\n" "Hello, World! \n" "How are you doing\n"

pr and printf are two very different formatting tools. pr takes text and prepares it for printing — paginating it, adding headers, arranging it into columns. printf takes a format string and data, and produces precisely formatted output — it’s the shell’s answer to C’s printf().

Key point: pr is about layout on a page. printf is about formatting values — numbers, strings, characters — with exact control over width, precision, and type. printf is the more commonly used tool in scripts; pr is a legacy tool that’s still useful for column layouts.

a – pr command

pr is used to paginate or columnate files. It was designed to prepare text for line printers, but it’s still useful for arranging output into columns and adding page headers.

Syntax:

pr [options] [file...]

Common options:

Option	Purpose
`-m`	Print files side by side (merge)
`-l N`	Set page length to N lines
`-N`	Format output in N columns
`-h HEADER`	Use HEADER as the page header
`-t`	Omit page headers and footers
`-d`	Double-space the output
`-n`	Number lines
`-w N`	Set page width to N columns
`-F`	Use form feeds between pages
`-s CHAR`	Use CHAR as the column separator

Examples:

# Look at the files
$ cat file1.txt
one
two
three
four
five

$ cat file2.txt
alpha
beta
gamma
delta
epsilon

# Print files side by side
$ pr -m -l 10 file1.txt file2.txt


2024-01-15 10:00                    Page 1


one                     alpha
two                     beta
three                   gamma
four                    delta
five                    epsilon

# Without headers, side by side
$ pr -m -t file1.txt file2.txt
one                     alpha
two                     beta
three                   gamma
four                    delta
five                    epsilon

# Format a single file into 3 columns
$ pr -3 -l 10 file1.txt


2024-01-15 10:00                    Page 1


one             two             three
four            five



# With -t (no headers)
$ pr -3 -t file1.txt
one             two             three
four            five

# Number lines
$ pr -n -t file1.txt
     1	one
     2	two
     3	three
     4	four
     5	five

# Double-space
$ pr -d -t file1.txt
one

two

three

four

five

# Custom header
$ pr -h "My Report" file1.txt


2024-01-15 10:00            My Report            Page 1


one
two
three
four
five

# Custom column separator
$ pr -m -t -s ' | ' file1.txt file2.txt
one | alpha
two | beta
three | gamma
four | delta
five | epsilon

Understanding the output:

┌──────────────────────────────────────────────┐
│           Default pr output                  │
│                                              │
│  (blank line)                                │
│  (blank line)                                │
│  2024-01-15 10:00          Page 1            │
│                                              │
│  (blank line)                                │
│  (blank line)                                │
│  one                                         │
│  two                                         │
│  three                                       │
│                                              │
│  (blank lines at end)                        │
│                                              │
│  Header: date + page number                  │
│  Footer: blank lines                         │
│                                              │
└──────────────────────────────────────────────┘

Use -t to suppress the headers and footers — that’s what you want most of the time when using pr in a pipeline.

Multi-column formatting:

# Two columns
$ pr -2 -t file1.txt
one             four
two             five
three

# Three columns
$ pr -3 -t file1.txt
one             two             three
four            five

# Four columns
$ pr -4 -t file1.txt
one             two             three           four
five

pr vs paste:

Tool	Effect
`pr -m`	Merges files side by side (like `paste` but with page formatting)
`paste`	Merges files side by side (TAB-separated, no page formatting)
`pr -N`	Splits one file into N columns
`column`	Formats into columns (more flexible, not always installed)

Note: pr is a legacy tool. For most modern uses, paste, column, or awk do a better job. But pr -m -t is a quick way to merge files side by side with a wider separator than paste‘s TAB.

b – printf command

printf is used to format and print data to the screen. It can display strings, integers, floating-point numbers, and characters. It’s the shell’s equivalent of C’s printf() — and it’s one of the most useful tools in scripting.

Syntax:

printf FORMAT [ARGUMENTS...]

Common format specifiers:

Specifier	Purpose
`%s`	Print a string
`%d`	Print a decimal integer
`%f`	Print a floating-point number
`%x`	Print a hexadecimal number
`%o`	Print an octal number
`%c`	Print a single character
`%e`	Print in scientific notation
`%%`	Print a literal `%`

Width and precision:

Format	Meaning
`%5d`	Right-align in 5 columns
`%-5d`	Left-align in 5 columns
`%05d`	Zero-pad to 5 digits
`%.2f`	2 decimal places
`%8.2f`	Width 8, 2 decimals
`%10s`	Right-align string in 10 columns
`%-10s`	Left-align string in 10 columns

Escape sequences:

Escape	Meaning
`\n`	Newline
`\t`	Tab
`\\`	Backslash
`\a`	Alert (bell)
`\r`	Carriage return
`\b`	Backspace
`\0NNN`	Octal character
`\xHH`	Hex character

Examples:

# Basic string and number substitution
$ printf "My favorite number is %d and my favorite letter is %c.\n" 42 'A'
My favorite number is 42 and my favorite letter is A.

# Floating-point with precision
$ printf "Pi is approximately %.2f\n" 3.14159
Pi is approximately 3.14

# %b — interpret escape sequences in the argument
$ printf "%b\n" "Hello, World! \n" "How are you doing\n"
Hello, World! 
How are you doing

# String formatting
$ printf "Name: %s, Age: %d\n" "Alice" 30
Name: Alice, Age: 30

# Multiple arguments — the format repeats
$ printf "%s\n" one two three four
one
two
three
four

# Width and alignment
$ printf "|%10s|%-10s|\n" "right" "left"
|     right|left      |

# Zero-padding
$ printf "%05d\n" 42
00042

# Hexadecimal and octal
$ printf "%x %o\n" 255 8
ff 10

# Scientific notation
$ printf "%e\n" 1234567
1.234567e+06

# Multiple specifiers
$ printf "%-10s %5d %8.2f\n" "apple" 5 1.234
apple          5     1.23

# Table-like output
$ printf "%-15s %-10s %5s\n" "Name" "Dept" "Score"
$ printf "%-15s %-10s %5d\n" "Alice" "Eng" 95
$ printf "%-15s %-10s %5d\n" "Bob" "Math" 87
Name            Dept       Score
Alice           Eng           95
Bob             Math          87

# Literal percent sign
$ printf "100%% complete\n"
100% complete

# Escape sequences
$ printf "Line 1\nLine 2\nLine 3\n"
Line 1
Line 2
Line 3

# Tabs
$ printf "col1\tcol2\tcol3\n"
col1	col2	col3

# Alert/bell
$ printf "Done\a\n"

# Character from code
$ printf "\x41\n"
A

# Reuse format with multiple arguments
$ printf "%d\n" 1 2 3 4 5
1
2
3
4
5

# Format cycles if more args than specifiers
$ printf "%s: %d\n" a 1 b 2 c 3
a: 1
b: 2
c: 3

printf vs echo:

Aspect	printf	echo
Formatting	Full control	Limited
Portability	POSIX-standard	Shell-dependent
Escape handling	Explicit	Varies (`-e` in bash)
Newline	Only if you add `\n`	Added by default
Numbers	Format with precision	Just prints
Best for	Scripts, tables, reports	Quick messages

# echo adds a newline by default
$ echo "hello"
hello

# printf does NOT — you must add \n
$ printf "hello"
hello$ 

# With \n
$ printf "hello\n"
hello

Building a table with printf:

$ printf "%-15s %-10s %s\n" "NAME" "DEPT" "SCORE"
$ printf "%-15s %-10s %d\n" "Alice" "Eng" 95
$ printf "%-15s %-10s %d\n" "Bob" "Math" 87
$ printf "%-15s %-10s %d\n" "Charlie" "Sci" 92
NAME            DEPT       SCORE
Alice           Eng        95
Bob             Math       87
Charlie         Sci        92

Formatting numbers in a loop:

$ for i in 1 2 3 4 5; do
    printf "Item %03d: %s\n" "$i" "processed"
  done
Item 001: processed
Item 002: processed
Item 003: processed
Item 004: processed
Item 005: processed

Converting between number bases:

$ printf "Decimal: %d, Hex: %x, Octal: %o\n" 255 255 255
Decimal: 255, Hex: ff, Octal: 377

Printing a character from its ASCII code:

$ printf "ASCII 65 = %c\n" 65
ASCII 65 = A

$ printf "\x48\x65\x6c\x6c\x6f\n"
Hello

Using %b for escape sequences in arguments:

$ printf "%b\n" "Line 1\nLine 2"
Line 1
Line 2

$ printf "%s\n" "Line 1\nLine 2"
Line 1\nLine 2
# %s treats the argument literally

Difference between %s and %b:

Specifier	Behavior
`%s`	Prints the string literally — no escape processing
`%b`	Processes `\n`, `\t`, etc. in the argument

$ printf "%s\n" "Hello\nWorld"
Hello\nWorld

$ printf "%b\n" "Hello\nWorld"
Hello
World

⚠️ Warning: Unlike echo, printf requires a format string. If you pass a variable that starts with - or contains %, things can break. Always use printf '%s\n' "$var" when you just want to print a variable safely:
$ var="100% done"
$ printf "$var\n"     # ❌ % is a format specifier
$ printf '%s\n' "$var"  # ✅ safe

Complete Example Session

# ============================================
# PART 1: PR — MERGE FILES SIDE BY SIDE
# ============================================

$ cat file1.txt
one
two
three
four
five

$ cat file2.txt
alpha
beta
gamma
delta
epsilon

$ pr -m -l 10 file1.txt file2.txt


2024-01-15 10:00                    Page 1


one                     alpha
two                     beta
three                   gamma
four                    delta
five                    epsilon

# Without headers
$ pr -m -t file1.txt file2.txt
one                     alpha
two                     beta
three                   gamma
four                    delta
five                    epsilon

# ============================================
# PART 2: PR — COLUMNATE A SINGLE FILE
# ============================================

$ pr -3 -l 10 file1.txt


2024-01-15 10:00                    Page 1


one             two             three
four            five



$ pr -3 -t file1.txt
one             two             three
four            five

# ============================================
# PART 3: PR — NUMBER LINES
# ============================================

$ pr -n -t file1.txt
     1	one
     2	two
     3	three
     4	four
     5	five

# ============================================
# PART 4: PR — CUSTOM HEADER
# ============================================

$ pr -h "My Report" file1.txt


2024-01-15 10:00            My Report            Page 1


one
two
three
four
five

# ============================================
# PART 5: PRINTF — BASIC FORMATTING
# ============================================

$ printf "My favorite number is %d and my favorite letter is %c.\n" 42 'A'
My favorite number is 42 and my favorite letter is A.

$ printf "Pi is approximately %.2f\n" 3.14159
Pi is approximately 3.14

$ printf "%b\n" "Hello, World! \n" "How are you doing\n"
Hello, World! 
How are you doing

# ============================================
# PART 6: PRINTF — WIDTH AND ALIGNMENT
# ============================================

$ printf "|%10s|%-10s|\n" "right" "left"
|     right|left      |

$ printf "%05d\n" 42
00042

$ printf "%-15s %-10s %5s\n" "Name" "Dept" "Score"
$ printf "%-15s %-10s %5d\n" "Alice" "Eng" 95
$ printf "%-15s %-10s %5d\n" "Bob" "Math" 87
Name            Dept       Score
Alice           Eng           95
Bob             Math          87

# ============================================
# PART 7: PRINTF — NUMBER BASES
# ============================================

$ printf "Decimal: %d, Hex: %x, Octal: %o\n" 255 255 255
Decimal: 255, Hex: ff, Octal: 377

$ printf "%e\n" 1234567
1.234567e+06

# ============================================
# PART 8: PRINTF — ESCAPE SEQUENCES
# ============================================

$ printf "Line 1\nLine 2\nLine 3\n"
Line 1
Line 2
Line 3

$ printf "col1\tcol2\tcol3\n"
col1	col2	col3

$ printf "\x48\x65\x6c\x6c\x6f\n"
Hello

# ============================================
# PART 9: PRINTF — CYCLING FORMAT
# ============================================

$ printf "%d\n" 1 2 3 4 5
1
2
3
4
5

$ printf "%s: %d\n" a 1 b 2 c 3
a: 1
b: 2
c: 3

# ============================================
# PART 10: PRINTF — %s vs %b
# ============================================

$ printf "%s\n" "Hello\nWorld"
Hello\nWorld

$ printf "%b\n" "Hello\nWorld"
Hello
World

# ============================================
# PART 11: COMBINING PR AND PRINTF
# ============================================

# Generate a report with printf
$ printf "%-10s %5s\n" "Alice" 95
$ printf "%-10s %5s\n" "Bob" 87
Alice         95
Bob           87

# Columnate a list with pr
$ ls | pr -3 -t
docs            notes.txt       todo.txt
readme.md       scripts         work

# ============================================
# PART 12: REAL-WORLD USES
# ============================================

# Numbered list in a script
$ for f in *.txt; do
    printf "%3d: %s\n" $((i++)) "$f"
  done
  1: file1.txt
  2: file2.txt
  3: file3.txt

# Tabular report
$ printf "%-20s %-15s %s\n" "USER" "SHELL" "HOME"
$ while IFS=: read -r user _ _ _ _ home shell; do
    printf "%-20s %-15s %s\n" "$user" "$shell" "$home"
  done < /etc/passwd | head -5
USER                 SHELL           HOME
root                 /bin/bash       /root
daemon               /usr/sbin/nologin /usr/sbin
bin                  /usr/sbin/nologin /bin
sys                  /usr/sbin/nologin /dev
sync                 /bin/sync       /bin

# Progress with zero-padded numbers
$ for i in $(seq 1 100); do
    printf "\rProcessing: %03d/100" "$i"
    sleep 0.01
  done
echo
Processing: 100/100

Quick Reference

pr

Command	Purpose
`pr FILE`	Format with headers
`pr -t FILE`	No headers
`pr -m A B`	Merge side by side
`pr -m -t A B`	Merge without headers
`pr -N -t FILE`	N columns
`pr -l N FILE`	Page length N
`pr -h HEADER FILE`	Custom header
`pr -n FILE`	Number lines
`pr -d FILE`	Double-space
`pr -s CHAR A B`	Column separator
`pr -w N FILE`	Page width

printf — Specifiers

Specifier	Purpose
`%s`	String
`%d`	Decimal integer
`%f`	Float
`%x`	Hex
`%o`	Octal
`%c`	Character
`%e`	Scientific
`%%`	Literal `%`
`%b`	String with escapes

printf — Width/Precision

Format	Meaning
`%5d`	Right-align width 5
`%-5d`	Left-align width 5
`%05d`	Zero-pad to 5
`%.2f`	2 decimals
`%8.2f`	Width 8, 2 decimals
`%10s`	Right-align string
`%-10s`	Left-align string

printf — Escapes

Escape	Meaning
`\n`	Newline
`\t`	Tab
`\\`	Backslash
`\a`	Bell
`\r`	Carriage return
`\b`	Backspace
`\xHH`	Hex char
`\0NNN`	Octal char

printf vs echo

Aspect	printf	echo
Format control	Full	Limited
Escape handling	Explicit	`-e` in bash
Newline	Manual `\n`	Automatic
Portability	POSIX	Shell-dependent
Numbers	Full formatting	Plain

Best Practices

✅ Do This:

# Use -t with pr for pipeline-friendly output
pr -m -t file1 file2                  # ✅

# Use printf for tables
printf "%-15s %5s\n" "Name" "Score"  # ✅

# Use %s when printing variables safely
printf '%s\n' "$var"                  # ✅

# Add \n explicitly with printf
printf "hello\n"                      # ✅

# Use width specifiers for alignment
printf "%05d\n" 42                    # ✅

# Use %b when you want escape handling
printf "%b\n" "line1\nline2"          # ✅

# Use printf in scripts instead of echo
printf "Error: %s\n" "$msg" >&2       # ✅

❌ Don’t Do This:

# Don't forget \n with printf
printf "hello"                        # ❌ no newline

# Don't pass user input as the format string
printf "$user_input"                  # ❌ format injection

# Don't use pr without -t in pipelines
pr file1 file2 | grep foo             # ❌ headers pollute

# Don't use echo -e in portable scripts
echo -e "line1\nline2"                # ❌ not POSIX

# Don't rely on echo's behavior for escapes
echo "line1\nline2"                   # ❌ shell-dependent

# Don't forget width for alignment
printf "%s %s\n" "a" "b"              # ⚠️  no alignment

Common Pitfalls

Pitfall	Problem	Solution
`printf` no newline	Output runs together	Add `\n`
`%` in variable	Format injection	Use `printf '%s' "$var"`
`pr` headers in output	Pollutes pipelines	Use `-t`
`%s` vs `%b`	Escapes not processed	Use `%b` when needed
Missing arguments	Empty output	Match args to specifiers
Wrong width	Misaligned columns	Use `%-Ns` consistently
`echo -e`	Not portable	Use `printf`
Locale decimals	Comma vs dot	Set `LC_ALL=C`

Real-World Examples

1. Merge Two Files Side by Side

$ pr -m -t names.txt scores.txt
alice           95
bob             87
charlie         92

2. Print in Three Columns

$ pr -3 -t file1.txt
one             two             three
four            five

3. Custom Page Header

$ pr -h "Monthly Report" data.txt > report.txt

4. Format a Number with Leading Zeros

$ printf "%05d\n" 42
00042

5. Print Pi with Precision

$ printf "Pi is approximately %.2f\n" 3.14159
Pi is approximately 3.14

6. Build a Table

$ printf "%-15s %-10s %5s\n" "NAME" "DEPT" "SCORE"
$ printf "%-15s %-10s %5d\n" "Alice" "Eng" 95
$ printf "%-15s %-10s %5d\n" "Bob" "Math" 87
NAME            DEPT       SCORE
Alice           Eng           95
Bob             Math          87

7. Convert to Hex

$ printf "0x%x\n" 255
0xff

8. Print with Escape Sequences

$ printf "Line 1\nLine 2\nLine 3\n"
Line 1
Line 2
Line 3

9. Print a Character from ASCII

$ printf "ASCII 65 = %c\n" 65
ASCII 65 = A

10. Cycle Format with Arguments

$ printf "%s: %d\n" a 1 b 2 c 3
a: 1
b: 2
c: 3

11. Progress Bar with `\r`

$ for i in $(seq 1 100); do
    printf "\rProgress: %3d%%" "$i"
    sleep 0.01
  done
echo
Progress: 100%

12. Number Files in a Loop

$ i=1
$ for f in *.txt; do
    printf "%3d: %s\n" $i "$f"
    i=$((i+1))
  done
  1: file1.txt
  2: file2.txt
  3: file3.txt

13. Columnate `ls` Output

$ ls | pr -3 -t
docs            notes.txt       todo.txt
readme.md       scripts         work

14. Safe Variable Printing

$ var="100% done"
$ printf '%s\n' "$var"
100% done

15. Error Messages in Scripts

$ printf "Error: %s (code %d)\n" "File not found" 2 >&2
Error: File not found (code 2)

16. Format a Date

$ printf "Year: %d, Month: %02d, Day: %02d\n" 2024 1 15
Year: 2024, Month: 01, Day: 15

17. Right-Align a Column of Numbers

$ for n in 5 100 42 1000 7; do
    printf "%6d\n" "$n"
  done
     5
   100
    42
  1000
     7

18. Side-by-Side Comparison

$ paste <(printf "%-10s\n" old1 old2 old3) \
        <(printf "%-10s\n" new1 new2 new3)
old1       new1
old2       new2
old3       new3

Visual: pr and printf

┌──────────────────────────────────────────────┐
│                pr -m -t                      │
│                                              │
│  file1:      file2:      output:             │
│  one         alpha       one        alpha    │
│  two         beta        two        beta     │
│  three       gamma       three      gamma    │
│                                              │
│  Merges side by side (no headers)            │
│                                              │
└──────────────────────────────────────────────┘

┌──────────────────────────────────────────────┐
│              pr -3 -t                        │
│                                              │
│  file:           output:                     │
│  one             one    two    three         │
│  two             four   five                 │
│  three                                       │
│  four                                        │
│  five                                        │
│                                              │
│  Splits into columns                         │
│                                              │
└──────────────────────────────────────────────┘

┌──────────────────────────────────────────────┐
│            printf "%-10s %5d\n"              │
│                                              │
│  Format: %-10s    %5d                        │
│          │        │                          │
│          │        └─ right-align 5 wide      │
│          └────────── left-align 10 wide      │
│                                              │
│  Args:   "apple"  5                          │
│  Output: apple          5                    │
│                                              │
│  Exact control over every character          │
│                                              │
└──────────────────────────────────────────────┘

Summary

Command	Purpose	Example
`pr FILE`	Format with headers	`pr file1.txt`
`pr -t FILE`	No headers	`pr -t file1.txt`
`pr -m -t A B`	Merge side by side	`pr -m -t file1.txt file2.txt`
`pr -3 -t FILE`	3 columns	`pr -3 -t file1.txt`
`pr -l N FILE`	Page length N	`pr -l 10 file1.txt`
`pr -h H FILE`	Custom header	`pr -h "Report" file1.txt`
`pr -n FILE`	Number lines	`pr -n file1.txt`
`printf "%d" N`	Integer	`printf "%d\n" 42`
`printf "%s" S`	String	`printf "%s\n" "hello"`
`printf "%f" N`	Float	`printf "%f\n" 3.14`
`printf "%.2f" N`	2 decimals	`printf "%.2f\n" 3.14159`
`printf "%c" N`	Character	`printf "%c\n" 65`
`printf "%x" N`	Hex	`printf "%x\n" 255`
`printf "%o" N`	Octal	`printf "%o\n" 8`
`printf "%e" N`	Scientific	`printf "%e\n" 1234567`
`printf "%-Ns" S`	Left-align	`printf "%-10s\n" "x"`
`printf "%Nd" N`	Right-align	`printf "%5d\n" 42`
`printf "%0Nd" N`	Zero-pad	`printf "%05d\n" 42`
`printf "%b" S`	Escapes in arg	`printf "%b\n" "a\nb"`
`printf "%%"`	Literal %	`printf "100%%\n"`

Key takeaways:

pr paginates and columnates — use -t to suppress headers in pipelines
pr -m -t A B merges two files side by side
pr -N -t FILE splits one file into N columns
printf gives you precise control over output format — it’s the scripting standard
%s for strings, %d for integers, %f for floats, %c for characters, %x/%o for other bases
Use %.2f for decimal precision, %05d for zero-padding, %-10s for left-alignment
printf does not add a newline — include \n explicitly
%b interprets escape sequences in the argument; %s prints literally
Prefer printf over echo in scripts — it’s portable, predictable, and powerful
Use printf '%s\n' "$var" to safely print variables that might contain % or -

Remember: pr is a layout tool — use it when you want columns or a printable page. printf is a formatting engine — use it whenever you need exact control over how values appear. In scripts, printf replaces both echo and awk‘s formatted printing for most cases. Learn the width and precision specifiers, and you can build clean tables, progress bars, and reports in a single line. And always quote variables when passing them to printf — or you’ll get format surprises.

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