Detect Script Line Endings with file

You need to know whether a script is shell text with CRLF or normal Unix line endings.

Command

file script.sh

Before you run this

System impact: Read-only. Low when scoped to the shown target.

When not to use it: Do not treat file output as proof the script is safe to execute.

File type and line-ending hints such as shell script text executable with CRLF line terminators.

Read-only. Nothing changes. The command reads current state and prints diagnostic evidence.

Recovery / rollback: no state is changed.

Use when `cat -v` suggests hidden carriage returns.

Do not treat file output as proof the script is safe to execute.

Example run

These are the commands shown for inspection. Treat them as an example, not proof that your system will behave identically.

next steps

Linux Survival Basics Read-only

The hidden carriage return is often the whole bug.

head -1 script.sh | cat -v

Linux Survival Basics Can be slow

Find exactly which lines still contain carriage returns.

grep -n $'\r' script.sh | head

Linux Survival Basics Read-only

For one package, dpkg-query gives a clean status line.

dpkg-query -W -f='${Status} ${Version}\n' openssl

Linux Survival Basics Can be slow

A quick extension count can show whether expected content made it into the source tree.

find source -type f -printf '%f\n' | sed -n 's/.*\.//p' | sort | uniq -c | sort -nr

Linux Survival Basics Can be slow

The disk was full, but guessing at folders was the slow part.

find /var -type f -printf '%s %p\n' | sort -nr | head -20

next diagnostic step

Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.