A technical journey to resolving line ending issues in Drupal installations

In the ever-evolving landscape of web development, technical challenges are par for the course. One such challenge recently encountered involved a Drupal installation, where the popular command-line tool Drush failed to execute correctly. This article delves into the issue, the diagnostic steps undertaken, and the resolution achieved, offering insights for professionals navigating similar technical hurdles.

Understanding the issue

During routine operations within a Drupal environment, an error surfaced when attempting to execute Drush:

/usr/bin/env: 'sh\r': No such file or directory

This cryptic message signalled a problem with the Drush executable script, preventing essential administrative tasks from proceeding. The error hinted at a misinterpretation of the shebang (`#!/usr/bin/env sh`) due to the presence of an unexpected carriage return character (`\r`), commonly associated with Windows-style line endings (CRLF) instead of the Unix-style (LF).

Diagnosing the problem

To address the issue systematically, a series of diagnostic commands were employed to pinpoint the root cause.

Check using file command

The initial step involved verifying the file type and line endings of the Drush wrapper script using the `file` command:

file vendor/bin/drush

Expected output for correct line endings:

vendor/bin/drush: POSIX shell script, ASCII text executable

An output indicating CRLF line terminators would reveal the presence of Windows-style line endings, confirming the suspected issue.

The response received was

vendor/bin/drush: a /usr/bin/env sh script, ASCII text executable

Check using cat and od

Further verification was conducted using `cat` and `od` (octal dump) to inspect the first line of the script:

head -n 1 vendor/bin/drush | od -c

Expected output without `\r`:

0000000   #   !   /   u   s   r   /   b   i   n   /   e   n   v       s  
0000020   h   \n
0000022

However, the actual response revealed:

0000000   #   !   /   u   s   r   /   b   i   n   /   e   n   v       s
0000020   h   \r  \n
0000023

The presence of `\r` before `\n` confirmed the existence of Windows-style line endings, corroborating the initial hypothesis.

head -n 1 vendor/drush/drush/drush | od -c

Expected output without `\r`:

0000000   #   !   /   u   s   r   /   b   i   n   /   e   n   v       s
0000020   h  \r  \n
0000023

Confirming the presence of `\r` characters

To ensure a comprehensive understanding, the presence of carriage return characters was further validated using two distinct methods:

A. using cat -v

The `cat -v` command makes non-printable characters visible:

cat -v vendor/bin/drush | head -n 1

Response

#!/usr/bin/env sh^M

The `^M` symbol unequivocally indicates a `\r` character at the end of the shebang line.

B. using od -c

Employing `od -c` provided a character-by-character representation:

head -n 1 vendor/bin/drush | od -c

Response

0000000   #   !   /   u   s   r   /   b   i   n   /   e   n   v       s
0000020   h   \r  \n
0000023

This output mirrored the previous findings, reaffirming the issue.

Converting line endings to unix-style (lf)

With the problem clearly identified, the next step was to rectify the line endings to align with Unix standards. The `sed` utility proved invaluable in this conversion.

Using sed

The following command was executed to remove the carriage return characters:

sed -i 's/\r$//' vendor/bin/drush
sed -i 's/\r$//' vendor/drush/drush/drush

This command targets and eliminates the `\r` character at the end of each line, effectively converting CRLF to LF line endings.

Ensuring correct line endings for all related Drush scripts

Addressing the wrapper script alone was insufficient; the actual Drush executable also required attention to prevent recurrence of the error.

A. verify and convert vendor/drush/drush/drush using sed

A similar `sed` command was applied to the Drush executable:

sed -i 's/\r$//' vendor/drush/drush/drush

Post-conversion, verification ensured the absence of `\r` characters:

head -n 1 vendor/drush/drush/drush | od -c

Expected output

0000000   #   !   /   u   s   r   /   b   i   n   /   e   n   v       p  
0000020   h   p   p  \n
0000024

B. ensure executable permissions

After rectifying the line endings, executable permissions were reaffirmed to guarantee proper script execution:

chmod +x vendor/bin/drush
chmod +x vendor/drush/drush/drush

Verification of permissions yielded:

-rwxr-xr-x 1 user group ... vendor/bin/drush
-rwxr-xr-x 1 user group ... vendor/drush/drush/drush

Testing drush execution

With all adjustments in place, Drush functionality was reassessed:

drush --version

Expected output and actual result

Drush Commandline Tool 13.3.0

Subsequent execution of a basic Drush command confirmed operational integrity:

drush status

This command successfully displayed the Drupal installation's status without triggering errors.

Lessons learned and best practices

This technical journey underscores several pivotal lessons and best practices for IT professionals:

1. Meticulous Diagnosis: Employing a combination of diagnostic tools (`file`, `cat -v`, `od -c`) ensures a thorough understanding of underlying issues.
2. Understanding Environment Nuances: Awareness of differences between operating systems, such as line ending conventions, is crucial in multi-platform development environments.
3. Utilising Appropriate Tools: Leveraging utilities like `sed` for text processing can efficiently resolve common scripting issues.
4. Maintaining Executable Permissions: Ensuring correct file permissions prevents execution-related errors and enhances security.
5. Preventing Future Issues: Configuring version control systems (e.g., Git) to handle line endings appropriately (`core.autocrlf` settings, `.gitattributes` files) can avert similar problems in collaborative and cross-platform projects.
6. Continuous Learning and Adaptation: Technical challenges, while daunting, present opportunities to deepen expertise and refine problem-solving skills.

The wrap

Navigating the complexities of Drupal installations and command-line tools like Drush requires a blend of technical acumen and systematic troubleshooting. The issue of incorrect line endings, though seemingly minor, can disrupt critical workflows. By methodically diagnosing the problem, applying targeted fixes, and instituting preventative measures, ensure robust and resilient web development environments. This experience not only resolved an immediate technical glitch but also reinforced best practices essential for maintaining seamless operations in diverse development ecosystems.