Shell 脚本打印根目录而不是文件的第一行

Question

我正在尝试读取文件的第一行，tests/test_reader.cc .在引用head -n 1 filename和read -r VAR < filename的无数SO问题之后，我尝试了两者，但在这两个问题中，都给出了以下内容：

/Applications /Library /Network /System /User Information /Users /Volumes /bin /cores /dev /etc /home /net /opt /private /sbin /tmp /usr /usr alias /var

我尝试的脚本如下：

extract-libs.sh：版本1

#!/bin/sh
SOURCE="$1"
read -r LINE < $SOURCE
echo $LINE
echo ${LINE:0:2}

extract-libs.sh：版本2

#!/bin/sh
SOURCE="$1"
# LINE=`cat $SOURCE | head -n 1`
LINE=`head -n 1 $SOURCE`
echo $LINE
echo ${LINE:0:2}

输出（两者）如下所示：

tests/test_reader.cc
/Applications /Library /Network /System /User Information /Users /Volumes /bin /cores /dev /etc /home /net /opt /private /sbin /tmp /usr /usr alias /var

调用：

sh extract-libs.sh tests/test_reader.cc

该文件具有权限：-rw-r--r--

test_reader.cc：

/* 
 * File:   test_reader.cc
 * Author: ###.####
 *
 * Created on May 6, 2016, 4:57 PM
 */
#include <cstdlib>
#include <iostream>
#include <cassert>
#include <core/config/reader.h>
using namespace df::config;
bool tests_passed[] = {
    0
};
int ecount = 0;
void check(df::config::reader);
int main(int argc, char** argv) {
  std::cout << "Test configuration readern";
  char file[] = "data/test/test_parser.txt";
  df::config::reader readr((char *) &file);
  readr.parse();
  check(readr);
  if (tests_passed[0]) {
    std::cout << "x1b[32mAll right. You can parse. Whoopee.x1b[0mn";
  } else {
    std::cout << "x1b[31mYou have a PROBLEM in your parsing code.x1b[0mn";
    ecount++;
  }
  return ecount;
}
void check(df::config::reader reader) {
  token root = reader.root;
  token::token_list root_children = root.get_children();
  assert(root_children.size() == 4);
  token object = root_children.front();
  assert(object.get_name().compare("OBJECT") == 0);
  assert(object.get_values().size() == 1);
  assert(object.get_values().front()._type == STRING);
  assert(object.get_values().front()._value._string.compare("TEST") == 0);
  assert(object.get_children().size() == 0);
  token whops = root_children.back();
  assert(whops.get_name().compare("TEST3") == 0);
  assert(whops.get_values().size() == 1);
  assert(whops.get_values().front()._type == STRING);
  assert(whops.get_values().front()._value._string.compare("WHOPS") == 0);
  token::token_list whops_children = whops.get_children();
  assert(whops_children.size() == 2);
  token parent1 = whops_children.front();
  assert(parent1.get_name().compare("PARENT1") == 0);
  assert(parent1.get_values().size() == 1);
  assert(parent1.get_values().front()._type == STRING);
  assert(parent1.get_values().front()._value._string.compare("FIELD1") == 0);
  token::token_list parent_1_children = parent1.get_children();
  assert(parent_1_children.size() == 2);
  token child1 = parent_1_children.front();
  assert(child1.get_name().compare("CHILD1") == 0);
  assert(child1.get_values().size() == 1);
  assert(child1.get_values().front()._type == STRING);
  assert(child1.get_values().front()._value._string.compare("FIELD2") == 0);
  token::token_list child_1_children = child1.get_children();
  assert(child_1_children.size() == 1);
  token grandchild1 = child_1_children.front();
  assert(grandchild1.get_name().compare("GRANDCHILD1") == 0);
  assert(grandchild1.get_values().size() == 1);
  assert(grandchild1.get_values().front()._type == INTEGER);
  assert(grandchild1.get_values().front()._value._int == 123);
  token child2 = parent_1_children.back();
  assert(child2.get_name().compare("CHILD2") == 0);
  assert(child2.get_values().size() == 0);
  assert(child2.get_children().size() == 0);
  token parent2 = whops_children.back();
  assert(parent2.get_name().compare("PARENT2") == 0);
  assert(parent2.get_values().size() == 0);
  token::token_list parent_2_children = parent2.get_children();
  assert(parent_2_children.size() == 1);
  token child3 = parent_2_children.front();
  assert(child3.get_name().compare("CHILD3") == 0);
  assert(child3.get_values().size() == 2);
  assert(child3.get_values().front()._type == STRING);
  assert(child3.get_values().back()._type == INTEGER);
  assert(child3.get_values().front()._value._string.compare("FIELD3") == 0);
  assert(child3.get_values().back()._value._int == 4);
  assert(child3.get_children().size() == 0);
  ::tests_passed[0] = true;
}

为什么extract-libs.sh没有得到文件的第一行？

Answer 1

使用 echo "${LINE:0:2}" .将此与echo /*进行比较.