📊 column — Format Output Into Columns

The most common use — take whitespace-separated data and align it:

# Without column — hard to read
echo "NAME STATUS PID MEMORY
nginx running 1234 45MB
sshd running 891 12MB
postgresql running 2201 380MB
redis stopped - -" | cat

# With column -t — instant alignment
echo "NAME STATUS PID MEMORY
nginx running 1234 45MB
sshd running 891 12MB
postgresql running 2201 380MB
redis stopped - -" | column -t

Process colon-delimited, CSV, or tab-separated data:

# Format /etc/passwd nicely
cut -d: -f1,3,6,7 /etc/passwd | column -t -s ':'

# Format a CSV (simple — no quoted fields)
echo "hostname,ip,role,os
web01,192.168.1.10,nginx,Ubuntu22
db01,192.168.1.20,postgresql,RHEL9
cache01,192.168.1.30,redis,Ubuntu22" | column -t -s ','

# Tab-delimited — from a script or spreadsheet export
printf "Server\tCPU\tRAM\tDisk\n" > /tmp/inv.tsv
printf "web01\t4\t16GB\t500GB\n" >> /tmp/inv.tsv
printf "db01\t16\t64GB\t2TB\n" >> /tmp/inv.tsv
column -t -s $'\t' /tmp/inv.tsv

Inject a header row without it being in the data stream:

# Add headers to ps output
ps aux --no-headers | awk '{print $1,$2,$3,$11}' | \
    column -t -N "USER,PID,CPU%,COMMAND"

# Add headers to a data file that has none
column -t -s ',' -N "HOST,IP,ROLE,OS" /tmp/servers.csv

# Right-align numeric columns with -R (util-linux 2.32+)
echo "server cpu mem disk
web01 4 16 500
db01 16 64 2000
cache01 2 8 100" | column -t -R 2,3,4

Without -t, column fills the terminal width with items arranged in columns — like ls does:

# List items across terminal width
ls /etc | column

# Force a specific width
ls /etc | column -c 60

# Display a list of packages in columns
rpm -qa --queryformat "%{NAME}\n" | sort | column

# Show available bash builtins in columns
compgen -b | column

Pipe common commands through column for instant readability:

# Mount points — cleaner than raw mount output
mount | grep -v "cgroup\|proc\|sys\|dev\|run" | \
    awk '{print $1, $3, $5}' | column -t

# Environment variables as a table
env | sort | column -t -s '='

# Listening ports — cleaner ss output
ss -tlnp | column -t

# /etc/hosts as aligned table
grep -v "^#\|^$" /etc/hosts | column -t

# crontab entries aligned
crontab -l | grep -v "^#" | column -t

#!/bin/bash
# Server inventory report using column

TMPFILE=$(mktemp)
trap 'rm -f "$TMPFILE"' EXIT

# Build data into temp file — header first
echo "HOSTNAME IP_ADDRESS CPU_CORES RAM_GB DISK_GB OS_VERSION" > "$TMPFILE"
echo "-------- ---------- --------- ------ ------- ----------" >> "$TMPFILE"

for host in web01 web02 db01 cache01; do
    # In real life these would be ssh calls
    printf "%s %s %s %s %s %s\n" \
        "$host" \
        "192.168.1.$(shuf -i 10-50 -n1)" \
        "$(shuf -i 2-16 -n1)" \
        "$(shuf -i 4-64 -n1)" \
        "$(shuf -i 100-2000 -n1)" \
        "RHEL9" >> "$TMPFILE"
done

# Format and display
echo ""
echo "=== Server Inventory ==="
echo ""
column -t "$TMPFILE"
echo ""

# column — best when data width is unknown at script write time
# Let column figure out widths from actual data
getent passwd | cut -d: -f1,3,7 | column -t -s ':'

# printf — best when you control the format and need exact widths
printf "%-20s %6s %s\n" "USERNAME" "UID" "SHELL"
printf "%-20s %6s %s\n" "--------" "---" "-----"
while IFS=: read -r user _ uid _ _ _ shell; do
    printf "%-20s %6s %s\n" "$user" "$uid" "$shell"
done < /etc/passwd

# Combine both — printf for header, column for data
printf "%-s\t%-s\t%-s\n" "USER" "UID" "SHELL"
printf "%-s\t%-s\t%-s\n" "----" "---" "-----"
cut -d: -f1,3,7 /etc/passwd | column -t -s ':'

Combining column with printf for polished bordered output:

#!/bin/bash
# Disk usage table with separator

SEP=$(printf '%0.s-' {1..55})

{
    echo "FILESYSTEM TOTAL USED AVAIL USE%"
    echo "$SEP"
    df -h --output=target,size,used,avail,pcent | \
        tail -n +2 | \
        grep -v "tmpfs\|udev"
} | column -t

# Hidden trick — use column on its own --table-* options (util-linux 2.30+)
# to add column separators
echo "NAME AGE CITY
Alice 34 Albany
Bob 28 Binghamton
Craig 65 Vestal" | column -t --table-columns NAME,AGE,CITY \
                              --table-right AGE