8e978fef9d
New: gotchas-skills.md (non-ASCII frontmatter, per-profile skill dirs). Updated: gotchas-bash.md (+((var++)) with zero), decisions.md (+python3 for JSON), process-lessons.md (+cat -A diagnostic). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Bash Gotchas
set -e silently kills scripts with complex subshell pipelines
set -euo pipefail can cause silent termination with no output when scripts use loops containing command substitutions, subshell calls, and pipelines. The script appears to produce no output and exits non-zero. For read-only/reporting tools, use set -uo pipefail without -e and handle errors explicitly.
grep interprets option-like strings as flags
grep -qF "$var" will fail if $var starts with -- (e.g., --dryrun). Always use -- to terminate option parsing: grep -qF -- "$var".
local keyword only works inside functions
Using local in the main script body (e.g., inside a for loop that isn't wrapped in a function) causes local: can only be used in a function. Either wrap the loop in a function or omit local.
set -e kills command substitution capturing non-zero exit codes
output=$(cmd) where cmd exits non-zero will trigger errexit before rc=$? on the next line executes. Use output=$(cmd) && rc=$? || rc=$? or output=$(cmd) || true to safely capture output from commands expected to fail.
((var++)) with var=0 triggers set -e exit
Arithmetic expressions like ((PASS++)) return the pre-increment value. When PASS=0, the result is 0 (falsy), which set -e treats as a failure and silently exits the script. Use PASS=$((PASS + 1)) instead — assignments always succeed regardless of the computed value.
file command marks shell scripts as "executable"
The file command returns strings like "Bourne-Again shell script, Unicode text, UTF-8 text executable" for shell scripts. Grepping for executable to detect binaries will false-positive on text scripts. Instead, grep for binary|image|archive and additionally check that the output does NOT contain text.