envsubst

all

Substitutes environment variables with their value in shell format strings. Variables to be replaced should be in either `${var}` or `$var` format.

Examples (4)

Replace environment variables in `stdin` and output to `stdout`

echo '$HOME' | envsubst

Replace environment variables in an input file and output to `stdout`

envsubst < path/to/input_file

Replace environment variables in an input file and output to a file

envsubst < path/to/input_file > path/to/output_file

Replace environment variables in an input file from a space-separated list

envsubst < path/to/input_file '$USER $SHELL $HOME'