DevOps Engineer
chmod for DevOps engineers: 755, 644, 600, and the permissions that matter
Use 755 for scripts and directories, 644 for configs and static files, 600 for SSH keys and secrets. Never use 777 in production. These three values cover almost every DevOps permission decision.
DevOps engineers reach for chmod daily in Dockerfiles, CI/CD pipelines, and server provisioning scripts. The three permissions that cover 90% of cases: 755 for executable scripts and directories, 644 for config files and static assets, and 600 for SSH private keys and secrets.
Why this matters for you
In a Dockerfile, RUN chmod 755 /entrypoint.sh is the standard for making an entrypoint executable. Config files mounted into containers should be 644 so the app can read them but not accidentally overwrite them. SSH private keys must be 600 or SSH refuses to use them, throwing a 'permissions too open' error. Never use 777 in production, it's a security audit failure waiting to happen.
Verdict
Use 755 for scripts and directories, 644 for configs and static files, 600 for SSH keys and secrets. Never use 777 in production. These three values cover almost every DevOps permission decision.
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