基于Bash脚本与Sed按规则提取ASCII文件特定位置记录

Got it, let's break this down into manageable parts to solve your problem. You need to process ASCII files with repeating 1NAME blocks (1 to 744 occurrences), extract values from a specific position in each block, output results to a text file with clear headers, and build a flexible Bash+Sed script that handles multiple input files. Here's a step-by-step solution:

1. Block Structure Assumption #

I’ll assume each 1NAME block follows a consistent line-based structure (adjust if your actual format differs):

1NAME
[Line 1 of block]
[Line 2 of block]
[Line N of block]

When you mention "specified重复位置的值", I’ll interpret that as the Nth line after the 1NAME header (we can tweak this later if you need to match a field name instead of a line position).

2. Core Sed Logic for Extraction #

Sed is ideal for pattern-based line grabbing. To extract the Nth line after every 1NAME entry:

• For the 2nd line (immediately after 1NAME):

  sed -n '/^1NAME$/{n;p}' your_file.txt
  

• For the 3rd line, add an extra n command:

  sed -n '/^1NAME$/{n;n;p}' your_file.txt
  

3. Reusable Bash Script #

Save this as extract_1NAME.sh — it lets you specify the target position, output file, and process multiple inputs:

#!/bin/bash

# Default configuration
TARGET_POSITION=2  # Default to 2nd line after 1NAME
OUTPUT_FILE="extracted_results.txt"

# Parse command-line arguments
while getopts "p:o:" opt; do
  case $opt in
    p) TARGET_POSITION="$OPTARG" ;;
    o) OUTPUT_FILE="$OPTARG" ;;
    \?) echo "Invalid option: -$OPTARG" >&2; exit 1 ;;
  esac
done

# Shift to access input files after flags
shift $((OPTIND - 1))

# Check if input files are provided
if [ $# -eq 0 ]; then
  echo "Usage: $0 -p <position> -o <output_file> <input_files...>"
  echo "Example: $0 -p 3 -o my_results.txt data1.txt data2.txt"
  exit 1
fi

# Generate dynamic Sed command: add (POSITION-1) number of 'n' commands
SED_SCRIPT="/^1NAME$/{$(printf 'n;' $(seq 1 $((TARGET_POSITION - 1))))p}"

# Write CSV header to output
echo "Input_File,Extracted_Value_Position_$TARGET_POSITION" > "$OUTPUT_FILE"

# Process each input file
for FILE in "$@"; do
  # Extract values and append to output (with filename context)
  sed -n "$SED_SCRIPT" "$FILE" | while read -r VALUE; do
    echo "$FILE,$VALUE" >> "$OUTPUT_FILE"
  done
done

echo "Done! Results saved to $OUTPUT_FILE"

4. How to Use #

1. Make the script executable:

   chmod +x extract_1NAME.sh
   

2. Run with your parameters:
   • Example: Extract the 3rd line after 1NAME from two files, output to results.csv:

     ./extract_1NAME.sh -p 3 -o results.csv file1.txt file2.txt
     

5. Example Output #

If file1.txt has:

1NAME
Apple
Red
Round
1NAME
Banana
Yellow
Long

Running the example command will produce results.csv:

Input_File,Extracted_Value_Position_3
file1.txt,Round
file1.txt,Long

6. Adjustments for Named Fields #

If your blocks use labeled fields (e.g., Color: Red), replace the SED_SCRIPT line with this to match field names instead of line positions:

SED_SCRIPT='/^1NAME$/{:loop;n;/Color:/{s/.*: //;p};b loop}'

This searches each 1NAME block for the Color: line, strips the label, and extracts the value.

内容的提问来源于stack exchange，提问作者coding_Stumps_me