Add Shell.append_if_missing() helper#39
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makermelissa merged 1 commit intoJun 16, 2026
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Adds the common grep-or-append idiom (grep -qxF line file || echo line >> file) as a reusable method, complementing reconfig(). The installer scripts repeat this pattern constantly for /etc/modules, blacklist, and config.txt entries. Uses re.escape so lines with regex metacharacters match literally.
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This is similar to reconfig, but it won't update an existing string.
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Jun 16, 2026
Drop the local append_if_missing helper now that it's available in the shared library (adafruit/Adafruit_Python_Shell#39).
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Adds
Shell.append_if_missing(file, line)— the common "add a line only if it isn't already there" idiom that the installer scripts repeat constantly for/etc/modules, modprobe blacklists, andconfig.txtentries.It's the Python equivalent of:
Complements the existing
reconfig()(which is uncomment-or-append for a regex pattern).append_if_missingis for the simpler exact-line case where you just want to guarantee a literal line is present without disturbing anything else.Uses
re.escapeso lines containing regex metacharacters (e.g.dtoverlay=i2s-mmap) are matched literally rather than as patterns.Context
Suggested by @makermelissa on adafruit/Raspberry-Pi-Installer-Scripts#398, where several converted installers each define a private copy of this helper. Landing it here lets those scripts share one implementation.
Testing
ruff format+ruff check+reuse lint(pre-commit) all pass.