How to Concatenate Strings in Bash

Applies to: Bash 4 and later on Linux (examples tested with Bash 5.1)

In Bash you join strings simply by writing them next to each other. There is no special operator. These are the patterns you need, all tested in Bash 5.1.

Put variables side by side

first="Ucartz"; second="Online"
full="$first $second"
echo "$full"                 # Ucartz Online

Use braces when text follows a variable

echo "${first}_${second}"    # Ucartz_Online
echo "$firstsuffix"          # empty: Bash looks for a variable called firstsuffix
echo "${first}suffix"        # Ucartzsuffix

Without braces, Bash reads as many letters, digits and underscores as it can as the variable name. Braces end the name.

Append with +=

path="/var/www"
path+="/html"
echo "$path"                 # /var/www/html

Numbers and text

n=5
msg="Items: $n"
echo "$msg"                  # Items: 5

Formatted strings with printf

printf -v line "%s-%03d" "$first" 7
echo "$line"                 # Ucartz-007

printf -v writes the result into a variable instead of printing it: useful for padded numbers, dates in file names and fixed-width output.

Join the elements of an array

parts=(a b c)
joined=$(IFS=,; echo "${parts[*]}")
echo "$joined"               # a,b,c

"${parts[*]}" joins with the first character of IFS; the subshell keeps the change of IFS from affecting the rest of the script.

Build a file name

backup="/backup/site-$(date +%F).tar.gz"
echo "$backup"               # for example /backup/site-2026-09-29.tar.gz

Common mistakes

• full = "$first$second" fails: no spaces around = in Bash assignments.
• Unquoted variables with spaces are split into several words; keep the quotes: "$full".

More: Bash arrays and Bash functions.