Shell Script

sh, bash, zsh and so on

date

2020-12-26

version

1

String

Get length:

${#str}

Substring / Slice:

${str:1:4}

Replace:

${v%.md}.rst

Heredoc

Syntax:

cat <<EOF
... Heredoc content
EOF

注解

Shell variables in heredoc will be expanded

Avoid shell expanding variables:

cat <<'EOF'
... Heredoc ${content}
EOF

Command Line Arguments

Number of pass-in arguments:

$#

The “pass-in argument list:

$* # Default, an **array**
$@ # Default, a **string**

The arguments of previous command:

!^      # First one
!$      # Last one
!*      # All
!:n     # N-th
!:n-m   # Range n~m