Unix sed command in Dockerfile

Question

Example found on GitHub:

FROM "xxx"/nginx-php-fpm:php73

MAINTAINER "xxx"

# Remove existing webroot, configure PHP session handler for Redis, install postgresql-client (pg_dump)
RUN rm -rf /usr/share/nginx/* && \
sed -i -e "s/memory_limit\s*=\s*.*/memory_limit = 256M/g" ${php_conf} && \
...

As I have understood the meaning of OPTIONS:
-i: "where to edit" and
-e: "script to be executed"

My question is: What does this line do?
sed -i -e "s/memory_limit\s*=\s*.*/memory_limit = 256M/g" ${php_conf}

When I try to run the line the response is: sed: no input files
How does it understand the ${php_conf}?

Clearly it doesn't, probably because you have not defined this variable. — tripleee, Feb 06 '19 at 13:12
https://github.com/wyveo/craftcms-docker/blob/craft3/Dockerfile is rather inefficient; somebody should tell the maintainer [how to combine multiple `sed` commands in one script.](/questions/7657647/combining-two-sed-commands) — tripleee, Feb 06 '19 at 13:15
https://gitlab.com/wyveo/nginx-php-fpm/blob/master/Dockerfile#L8 seems to be where the variable gets defined. This too has the same antipattern. — tripleee, Feb 06 '19 at 13:16

score 0 · Answer 1 · edited Mar 15 '19 at 13:36

0

That line is replacing all the matches memory_limit = ... to memory_limit = 256M in the php_conf file.
The problem in that Dockerfile is that you have not defined the environment variable php_conf and therefore there's no input file.

You could easily fix that by adding the env variable before your RUN command:

ENV php_conf /path/to/your/php_config

edited Mar 15 '19 at 13:36

GileBrt

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answered Feb 06 '19 at 14:08

Ricardo Jover

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Unix sed command in Dockerfile

1 Answers1