在 Linux 中，如何根据文本文件中包含的字符显示条目？

Question

我尝试过查找，但没有成功。想象一下我有一个包含以下内容的文本文件：

Ray Szeto [phone] friend
alex johnson [phone] family doctor 
Tom Podstawka [phone] dentist
Greg Ivan [phone] neighbour
Nikola Sandic [phone] friend from work
Tim Yu [phone] Jill's coach
Marvin Macalino [phone] gym
Paul Jakubiak [phone] grocery store
Karim Khalil [phone] friend
Denis Malino [phone] chiropractor
Timothy Hawn [phone] hair dresser
GREGORY FISH [phone] Dynasty restaurant
PAUL Demers [phone] neighbour
Tara Rathbone [phone] babysitter 
ROB Oxley [phone] friend from university
Robert Hartzell [phone] after-hour children clinic
Stephen Hawn [phone] repairman
Steve OXLEYRICH [phone] post office
Brenda Caverly [phone] babysitter
Sean Zheng [phone] neighbour
Ryan ZHENG [phone] Lawrence supermaket
Alexander Smith [phone] home renovation contractor

...假设我只想在终端中显示名称包含“alex”的条目，不区分大小写。我该怎么做呢？我知道过滤器类似于 %alex% 但我不知道执行此操作的确切命令。

.

Answer 1

# search for a word the long way
function find_text_the_long_way() {
    # upper case of the search term
    local upper_case_word="${1^^}"
    # one line read from the file
    local original_line=
    # same one line from file converted to upper case
    local upper_case_line=

    # read each line from standard input stream 
    while read original_line
    do
        # convert current line to upper case
        upper_case_line="${original_line^^}"

        # echo if the current line contains the search term 
        [[ "${upper_case_line//$upper_case_word/}" != "$upper_case_line" ]] && \
            echo "$original_line"
    done
}

find_text_the_long_way "alex" <"stack.txt"