tldr/pages/common/less-than.md

Less than

Redirect data to stdin. More information: https://gnu.org/software/bash/manual/bash.html#Redirecting-Input.

• Redirect a file to stdin (achieves the same effect as cat file.txt |):

{{command}} < {{path/to/file.txt}}

• Create a here document and pass that into stdin (requires a multiline command):

{{command}} << {{EOF}} <Enter> {{multiline_text}} <Enter> {{EOF}}

• Create a here string and pass that into stdin (achieves the same effect as echo string |):

{{command}} <<< {{string}}

• Process data from a file and write the output to another file:

{{command}} < {{path/to/file.txt}} > {{path/to/file2.txt}}

• Write a here document into a file:

cat << {{EOF}} > {{path/to/file.txt}} <Enter> {{multiline_data}} <Enter> {{EOF}}

• Disregard leading tabs (good for scripts with indentation but does not work for spaces):

cat <<- {{EOF}} > {{path/to/file.txt}} <Enter> {{multiline_data}} <Enter> {{EOF}}

• Pass command output to a program as a file descriptor:

diff <({{command1}}) <({{command2}})