Command Chaining

Execute multiple commands with conditional or sequential logic.

Operators

AND (&&)

Run second command only if first succeeds:

make && make install
# make install runs only if make succeeds

cd /project && npm install
# npm install runs only if cd succeeds

mkdir -p dir && cd dir && touch file
# Creates dir, enters it, creates file

OR (||)

Run second command only if first fails:

cd /nonexistent || echo "Directory not found"
# echo runs because cd failed

command || exit 1
# Exit script if command fails

test -f config || cp default.conf config
# Copy default only if config doesn't exist

Sequential (;)

Run commands in sequence regardless of exit codes:

echo "Start"; command; echo "End"
# All three run

cd /tmp; ls; pwd
# All run even if one fails

Combined Patterns

Build and Install

make clean && make && make install

Create If Not Exists

test -d "$dir" || mkdir -p "$dir"

Try Multiple Options

command1 || command2 || command3
# Tries each until one succeeds

Fallback with Message

./run.sh || echo "Script failed" && exit 1

Grouped Commands

(cd /project && make) || echo "Build failed"

Exit Codes

AND Chain

true && echo "runs"     # runs
false && echo "skipped" # skipped

OR Chain

true || echo "skipped"  # skipped
false || echo "runs"    # runs

Chain Exit Code

Exit code is from the last executed command:

true && false
echo $?  # 1 (from false)

false || true
echo $?  # 0 (from true)

Common Use Cases

Safe Directory Operations

cd /some/dir && rm -rf temp/
# Only deletes if cd succeeds

Conditional Execution

[ -f config.yml ] && source config.yml

Error Handling

command || { echo "Error" >&2; exit 1; }

Cleanup on Success

make && make test && make clean

With Other Features

With Pipes

cat file | grep pattern && echo "Found"
make 2>&1 | tee log && echo "Success"

With Redirection

command > output && echo "Saved"

With Variables

export DEBUG=1 && ./run.sh