printf

The printf command behaves similarly to the C printf() function and gives you more control over formatting

Print a sequence of numbers

for i in $(seq 0 99); do printf '%s\n' "$i"; done

Print alphabet in order

i=97; while [ $i -le 122 ]; do printf '%b\n' "\\$(printf '%03o' "$i")"; i=$((i+1)); done

Print a horizontal line (minimal ash where tput is not installed)

printf '%*s\n' "${COLUMNS:-80}" '' | tr ' ' "${1-_}"

Print a horizontal line (bash)

printf -v _hr "%*s" $(tput cols) && echo ${_hr// /${1--}}

Print a horizontal line (ash)

w=${COLUMNS:-80}; i=0; while [ $i -lt "$w" ]; do printf '%s' "${1--}"; i=$((i+1)); done; printf '\n'

Print date with colorized Date

printf "\033[33mDate:\033[37m %s\033[0m\n" "$(date)"

Print a random uuid

printf '%08x-%04x-%04x-%04x-%012x\n' $RANDOM$RANDOM $RANDOM $RANDOM $RANDOM $RANDOM$RANDOM$RANDOM

Print a random uuid in ash shell

hexdump -n16 -e '4/4 "%08x" 1 "\n"' /dev/urandom | sed 's/\(........\)\(....\)\(....\)\(....\)\(............\)/\1-\2-\3-\4-\5/'

Repeat printing string 5 times

printf 'hello world\n%.0s' {1..5}

Display each directory in $PATH on a separate sine

printf ${PATH//:/\\n}

List all files in every directory defined in $PATH

printf "%s\n" ${PATH//:/\/* }

Enumerate all executable files in $PATH with Absolute Paths

(IFS=:; for d in $PATH; do for f in "$d"/*; do [ -f "$f" ] && [ -x "$f" ] && printf '%s\n' "$f"; done done) | sort -u

Enumerate all executable filenames available in $PATH

(IFS=:; for d in $PATH; do for f in "$d"/*; do [ -f "$f" ] && [ -x "$f" ] && printf '%s\n' "${f##*/}"; done; done) | sort -u

Zero-pad integers to 4 digits

printf '%04d\n' 1 23 456

Left and right align text in columns

printf '%-10s %10s\n' "USER" "SHELL"

Print floating point numbers with precision

printf '%.3f\n' 3.1415926535

Print table headers with dynamic width

printf '%-15s %-10s %-5s\n' "Username" "Shell" "UID"

Convert decimal to hexadecimal

printf '0x%X\n' 255

Convert decimal to octal

printf '0%o\n' 755

Print binary representation (bash arithmetic)

printf '%08d\n' "$(echo "obase=2; 13" | bc)"

Escape special characters safely

printf '%q\n' 'hello world & $(rm -rf ~/somefile)'

Command substitution inside double quotes is executed BEFORE printf runs

printf '%s\n' "$(echo injected)"

Print NUL-terminated strings (for xargs -0)

printf '%s\0' file1 file2 file3

Generate a progress bar

p=30; w=50; printf '[%-*s] %d%%\n' "$w" "$(printf '%*s' $((p*w/100)) | tr ' ' '#')" "$p"

Print colored success and error messages

printf '\033[32m[OK]\033[0m Operation completed\n'

Timestamped log entry

printf '[%(%F %T)T] %s\n' -1 "Service started"

Print environment variables in key=value format

printf '%s=%q\n' USER "$USER"

Create formatted CSV output

printf '"%s","%s","%s"\n' "alice" "1000" "/bin/bash"