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"

PAdding characters in printf

line='----------------------------------------'
PROC_NAME='abc'
printf "%s %s [UP]\n" $PROC_NAME "${line:${#PROC_NAME}}"
PROC_NAME='abcdef'
printf "%s %s [UP]\n" $PROC_NAME "${line:${#PROC_NAME}}"

Padding characters at same length when using ping

list=(localhost google.com linux-shell.se idg.se thiswillfail)
C=1
for M in "${list[@]}"
do
    machine_indented=$(printf '%-20s' "$M")
    machine_indented=${machine_indented// /.}

    if ping -q -c 1  "$M" &>/dev/null ;  then
        printf "(%2d) %s CONNECTION \e[1;32mOK\e[0m\n" "$C" "$machine_indented"
    else
        printf "(%2d) %s CONNECTION \e[1;31mFAIL\e[0m\n" "$C" "$machine_indented"
    fi
    ((C=C+1))
done

Make a rectangle box that fits 3 lines vertical and a full horizontal line over entire screen

cols=$(stty size 2>/dev/null | cut -d' ' -f2 || echo 80)
# Topp
printf "+%$(($cols-2))s+\n" | tr " " "-"
# Sidor
for i in {1..3}; do
    printf "|%$(($cols-2))s|\n" " "
done
# Botten
printf "+%$(($cols-2))s+\n" | tr " " "-"

Print a vertical line

1) Example: 12) Example: 23) Example three - Write a vertical line on column 204) Print a vertical line that covers bottom to top5) Print a vertical line infront of df command in green color6) Draw a line on column 10 from bottom to top

for i in $(seq 1 10); do 
    printf "|\n"
done

v_line() {
    while IFS= read -r line; do
        printf "| %s\n" "$line"
    done
}

df -h | v_line

for i in $(seq 1 10); do
    printf "\033[%d;20H|" "$i"
done
echo -e "\033[11;1H"

rows=$(stty size 2>/dev/null | cut -d' ' -f1 || echo 24)

for ((i=1; i<=rows; i++)); do
    printf "|\n"
done

v_line() {
    local color="\033[1;32m" # Grön färg för linjen (valfritt)
    local reset="\033[0m"
    
    while IFS= read -r line; do
        printf "${color}|${reset} %s\n" "$line"
    done
}

df -h | v_line

rows=$(stty size 2>/dev/null | cut -d' ' -f1 || echo 24)

for i in $(seq 1 $rows); do
    # \033[rad;kolumnH flyttar markören
    printf "\033[%d;10H|" "$i"
done
printf "\033[%d;1H" "$rows"

Print a horizontal line over entire screen

1) Example 12) Example 23) Example 34) Example 45) Example 56) Example 67) Example 78) Example 8

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

printf '%*s' "$(tput cols)" '' | tr ' ' "${1--}"

for ((i=0; i<COLUMNS; i++)); do printf "${1--}"; done; echo

printf "%$(stty size | cut -d' ' -f2)s" " " | tr " " "${1--}"

printf "%$(stty size | cut -d' ' -f2)s" " " | tr " " "${1--}"

cols=$(stty size 2>/dev/null | awk '{print $2}')
: ${cols:=80} # Om stty failar, sätt till 80
for i in $(seq 1 $cols); do printf "${1--}"; done; echo

cols=${COLUMNS:-80}
printf "%${cols}s" " " | tr " " "${1--}"

hr() {
    local c=${1--}
    local cols
    cols=$(stty size 2>/dev/null | cut -d' ' -f2)
    [ -z "$cols" ] && cols=${COLUMNS:-80}
    
    # Skapa linjen effektivt utan externa binärer
    local line
    printf -v line "%*s" "$cols" ""
    echo "${line// /$c}"
}