ksh control statement

最新推荐文章于 2025-12-15 07:11:24 发布

原创最新推荐文章于 2025-12-15 07:11:24 发布 · 330 阅读

0 ·

CC 4.0 BY-SA版权

Shell 专栏收录该内容

22 篇文章

订阅专栏

本文通过几个具体的案例展示了Shell脚本中case和while语句的应用。包括文件类型判断、变量模式匹配、从文件及命令读取数据等实用场景。

Case Statement

Simple Case

case ${FileType} in
  SHELL)
    FileType=SHELL
    ;;
  C)
    FileType=CPP
    ;;
  JAVE)
    FileType=JAVA
    ;;
  (*)
    FileType=UNKNOW
    return 255
esac

Pattern Case 1

case ${VAR} in
    (ABC)                DO_COMMAND ;;
    (DE|FG)              DO_COMMAND ;;
    (????W)              DO_COMMAND ;;
    (????E)              DO_COMMAND ;;
    (01???|02???)        DO_COMMAND ;;
    (23???|42???)        DO_COMMAND ;;
    ([-p+n]*)            DO_COMMAND ;;
    ([+n]*)              DO_COMMAND ;;
    ([-p]*|all|cur)      DO_COMMAND ;;
    (*)                  DO_COMMAND ;;
esac

Pattern Case 2

 case "${Instream}-${Temporary}-${Concatenation}-${Generation#[-+]}" in
    (true-true-*-*)                    DO_COMMAND ;;
    (true-*-*-?*)                      DO_COMMAND ;;
    (*-true-*-?*)                      DO_COMMAND ;;
    (true-*-true-|*-true-true-)        DO_COMMAND ;;
    (true-*-false-|*-true-false-)      DO_COMMAND ;;
    (*-*-true-*)                       DO_COMMAND ;;
    (*-*-*-*)                          DO_COMMAND ;;
(*)                                DO_COMMAND ;;
esac

Pattern Case 3

foo='abcdef'
pattern='abc*'

case ${foo} in
    (${pattern})    DO_COMMAND ;;
    (*)             DO_COMMAND ;;
esac

While Statement

Read from file

while IFS=";" read VAR1 VAR2 VARDummy; do
    DO_COMMAND
done < ${INPUTFILE}
# Line of ${INPUTFILE} has 3 fields, separated with a ';'

Read from command

while read line
do
    DO_COMMAND
done

ls "*.sh" | while read File; do
    echo ${File}
done

cat ${OUT_FILE}| while read Line; do
    echo ${Line}
done

Read from variable

while read line; do
    DO_COMMAND
done <<-end_of_read
    ${VAR}           # or, $(echo ${VAR})
end_of_read

while read line; do
    DO_COMMAND
done <-end_of_read
    $(echo ${VAR} | tr ',' '\n')
end_of_read

echo ${VAR} | tr ',' '\n' | while read line; do
    DO_COMMAND
done