Summary
Shell programming, the glue that holds modern computer systems together, is as prevalent as ever—steadily in the top 10 most popular programming languages in widespread use. It is also quite complex, due to the structure of shell programs, their use of opaque software components, and their complex interactions with the broader environment. As a result, even when exercising an abundance of care, shell developers discover devastating bugs in their programs during or after their execution—when it is too late to reverse any of their unintended effects. Bugs in these applications therefore affect—
