shell 脚本小功能集合

Table of Contents

1 字符串处理

1.1 去掉空白

# 去前面空格
var="${var#"${var%%[![:space:]]*}"}"
# 去后面空格
var="${var%"${var##*[![:space:]]}"}"   
# 去掉首尾空白
trim_string() {
    # Usage: trim_string "   example   string    "
    : "${1#"${1%%[![:space:]]*}"}"
    : "${_%"${_##*[![:space:]]}"}"
    printf '%s\n' "$_"
}
$ trim_string "    Hello,  World    "
Hello,  World

# 整理参数
$ echo "  aa  bb " | xargs
aa bb

# 去掉所有空格
$ echo " a  b  c  "  | tr -d '[:space:]'
abc$
# 去掉前面的空格
$ echo " a  b  c  " | sed -e 's/^[[:space:]]*//'
# 去掉后面的空格
$ echo " a b c " | sed -e 's/[[:space:]]*$//'
# 去掉前后空格
echo " a b c  " | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//'

1.2 大小写转换

echo "Upper to Lower" | tr '[:upper:]' '[:lower:]'

# bash 4.0+ to lower
echo "${a,,}"
# bash 4.0+ to upper
echo "${a^^}"
# reverse case
echo "${a~~}"

1.3 判断是否包含子串

if [[ $var == *sub_string* ]]; then
    printf '%s\n' "sub_string is in var."
fi

# Inverse (substring not in string).
if [[ $var != *sub_string* ]]; then
    printf '%s\n' "sub_string is not in var."
fi

# This works for arrays too!
if [[ ${arr[*]} == *sub_string* ]]; then
    printf '%s\n' "sub_string is in array."
fi

# start with sub-string: *sub_string
# end with sub-string: sub_string*

# using a case statement
case "$var"
    *sub_string*)
        # Do
    ;;
    *)
        # Else
esac

2 gdb

2.1 设置变量

# 设置变量
(gdb) set var i = 10
# 设置地址为值
(gdb) set set {int}0x1236252 = 10
# 设置寄存器
set var $eax = 10

2.2 字符串

# 打印 char str1[] = "abcd";
(gdb) x/s str1
# 打印 wchar_t str2[] = L"abcd";
(gdb) x/ws str2

# 设置字符串, 也可以通过 set{char [n]} 0xxxxx = "ABCD"
(gdb) set main::str1 = "ABCD";

2.3 函数

# 正则搜索函数
(gdb) info functions pre[a-z]*
# 退出函数
(gdb) fin
# 执行函数
call func()
print func()

# 显示函数栈
(gdb) i frame
# 显示寄存器
(gdb) i registers

# 尾调用栈信息
(gdb) set debug entry-values 1
(gdb) i frame

2.4 断点

# 匿名空间设置断点
(gdb) b (anonymous namespace)::func
# 地址上打断点
(gdb) b *0x22222
# 文件行号上打断点
(gdb) b file.c:17
# 保存/恢复断点
(gdb) save breakpoints file-name-to-save
(gdb) source file-name-to-save
(gdb) info breakpoints
# 临时，一次性断点 tbreak
(gdb) tb xxx.c:12
# 条件断点
(gdb) b xxx.c:10 if i==10
# 忽略断点 1 一共 10 次
(gdb) ignore 1 10

2.5 观察点

# 设置观察点，变量变化时停下来
(gdb) watch var1
(gdb) watch *(int*)0x33333

# 令观察点只对特定线程生效
(gdb) wa var1 thread 3

# 读观察点，读取变量时生效
(gdb) rwatch var1
# 读写观察点
(gdb) awatch var1

2.6 打印内存

# 16 进制打印 10个字节
(gdb) x/10xb a
# 10 进制打印
(gdb) x/20ub a
# 2 进制打印
(gdb) x/16tb a

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