1 SC2050

koalaman edited this page 2017-07-13 14:16:11 -07:00

Table of Contents

• This expression is constant. Did you forget the $ on a variable?
• Problematic code:
• Correct code:
• Rationale:
• Exceptions:

This expression is constant. Did you forget the $ on a variable?

Problematic code:

if [ myvar = "test" ]
then
  echo "Test mode"
fi

Correct code:

if [ "$myvar" = "test" ]
then
  echo "Test mode"
fi

Rationale:

ShellCheck has found a [ .. ] or [[ .. ]] comparison that only involves literal strings. The intention was probably to check a variable or command output instead.

This is usually due to missing $ or bad quoting:

if [[ "myvar" = "test" ]]             # always false because myvar is a literal string
if [[ "$myvar" = "test" ]]            # correctly compares a variable

if [ 'grep -c foo bar' -ge 10 ]       # always false because grep doesn't run
if [ "$(grep -c foo bar)" -ge 10 ]    # correctly checks grep output

Exceptions:

None

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