如何从特定行启动 shell 脚本？

Question

#!/bin/sh
echo "install 1"
echo "install 2"
[ $? -eq 0 ] || exit $?;
cyberciti 
[ $? -eq 0 ] || exit $?;
echo "install 3"
echo "install 4"

上述脚本在第 4 行 (cyberciti) 失败。如何获取行号，并从该行开始重新运行脚本，在进行所需的更正后，跳过已执行的命令？

Answer 1

当你认为你经常需要做这样的事情时，你可以使用一个特殊的变量。并制作一个可选的命令行参数（默认从开头开始）告诉您从哪里开始。
非结构化版本如下所示：

#!/bin/sh
if [ $# -eq 1 ]; then
   PHASE=$1
else
   PHASE=1
fi
echo phase $PHASE

if [ ${PHASE} -eq 1 ]; then
        echo "install 1"
        (( PHASE = PHASE + 1 ))
fi

if [ ${PHASE} -eq 2 ]; then
        echo "install 2"
        [ $? -eq 0 ] || exit $?;
        (( PHASE = PHASE + 1 ))
fi

if [ ${PHASE} -eq 3 ]; then
        echo cyberciti
[ $? -eq 0 ] || exit $?;
        # Still phase 3, cyberciti is not a special phase

        echo "install 3"
        (( PHASE = PHASE + 1 ))
fi

if [ ${PHASE} -eq 4 ]; then
        echo "install 4"
        (( PHASE = PHASE + 1 ))
fi

一个改进是使用一个while循环：

#!/bin/sh
if [ $# -eq 1 ]; then
   PHASE=$1
else
   PHASE=1
fi

function phase2 {
        echo "install 2"
        [ $? -eq 0 ] || exit $?;
}

function phase3 {
        echo cyberciti
        [ $? -eq 0 ] || exit $?;
        # Still phase 3, cyberciti is not a special phase
        echo "install 3"
}

while [ ${PHASE} -lt 5 ]; do
        [ ${PHASE} -eq 1 ] && echo "install 1"
        [ ${PHASE} -eq 2 ] && phase2
        [ ${PHASE} -eq 3 ] && phase3
        [ ${PHASE} -eq 4 ] && echo "install 4"
        (( PHASE = PHASE + 1 ))
done

进一步的改进可能包括逻辑名称和一些可以在一个阶段内更改的特殊流控制。

编辑：使用案例构造进行改进

#!/bin/sh
if [ $# -eq 1 ]; then
   PHASE=$1
else
   PHASE=1
fi

function phase2 {
        echo "install 2"
        [ $? -eq 0 ] || exit $?;
}

function phase3 {
        echo cyberciti
        [ $? -eq 0 ] || exit $?;
        # Still phase 3, cyberciti is not a special phase
        echo "install 3"
}

endloop=false
while [ ${endloop} = false ]; do
   case ${PHASE} in
       1) echo "install 1" ;;
       2) phase2 ;;
       3) phase3 ;;
       4) echo "install 4" ;;
       5) endloop=true ;;
       *) echo "Phase ${PHASE} not supported" ;;
    esac
    (( PHASE = PHASE + 1 ))
done

Answer 2

#!/bin/sh
if [ $# -eq 1 ]; then
 PHASE=$1
else
 PHASE=1
fi
if [ ${PHASE} -le 6 ]; then
    echo "install 1 "
    echo "install 2 "
fi
if [ ${PHASE} -le 10 ]; then
  cyberciti
  [ $? -eq 0 ] || exit $?;
  echo "install 3 "
  [ $? -eq 0 ] || exit $?;
fi
if [ ${PHASE} -le 16 ]; then
    echo "install 4"
    [ $? -eq 0 ] || exit $?;
fi

这是我需要的最后一个脚本，当我们第一次运行时 (sh test.sh) 将在cyberciti 失败，然后我们只需要在用有效命令替换cyberciti 后从这一行运行，所以它通过新参数作为错误行（sh test.sh 11）从这一行恢复运行

Answer 3

跳过前 4 行（因此从第 5 行开始）：

tail --lines=+5 script.sh | sh

根据the man page，--lines=K表示output the last K lines, instead of the last 10; or use -n +K to output starting with the Kth。

感谢Aaron Digulla 他的回答here。编辑：感谢l0b0 阻止我的cat 来自taking over the world！