seep

Print stdin to terminal, then pipe into next process.

seep (short for see pipe and also to describe leaks in real pipes) has the purpose of letting you peek at what you're piping.

Usage

On Unix like systems, you can pass the output (stdout) of one process to the other as input, like this: echo "foo" | hexdump. In some cases, the output of the first command might contain information that a user might want to look at.

When the second process does not show the information it received, the user cannot see the information produced by the first program. This is where seep comes useful:

To look at the output of process one, we pipe it to seep and then pipe the output of seep to process two. seep will show us what information it receives and pass it over to process two:

$ ls | seep | grep src
Cargo.lock
Cargo.toml
LICENSE
README.md
scripts
src
target

src

(list files and dirs, show all with seep, show only containing "src")

Similarity to tee

The command tee is part of the coreutils and available on almost any Unix like system. It can be used to achieve similar things as seep, for example:

$ ls | tee $TTY | grep src
Cargo.lock
Cargo.toml
LICENSE
README.md
scripts
src
target
src

(list files and dirs, show all with tee, show only containing "src")

tee and seep do not have the same features. Currently, seep cannot output to files specified with cli arguments, and seep's focus lies on presenting information to the user.