shell ultimate guide

[zero2hj]

[zero2hj]

flow control

[[ -n "$initSQL" ]] && { $MYSQL_CMD -e"$initSQL" || exit 1; }
execute sql if not empty, exit 1 if execute encount error. note the space before and after {}

[zero2hj]

pipe and stdin

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cp command

The behavior of the cp command depends on whether the source and destination are files or directories, and the presence of a trailing slash (/) is a critical signal, especially for the destination.

[zero2hj]

grep -E -m -o