基于Bash与gdalinfo的TIFF栅格投影列示及NoData值一致性检查

Hey Rose, I've revised and expanded your original Bash script to cover both of your technical requirements. Let's break it down:

1. List Unique Projections Across TIFF Files #

To extract and list distinct projections from all TIFFs in your directory tree, we can parse the PROJCS line from gdalinfo output. Here's a clean, reliable script for this:

#!/bin/bash
basepath=/home/rose/Desktop/GreatExtentDSMnodatacleaned # Update your root directory
shopt -s globstar # Enable recursive directory matching

echo "=== Unique Projections in Directory Tree ==="
cd "$basepath"
# Recursively find all TIFF files and extract projections
for f in **/*.tif; do
  # Extract projection name (fallback to "Unknown" if none found)
  gdalinfo "$f" | grep -o 'PROJCS\["[^"]*"\]' | sed 's/PROJCS\[//; s/"//g' || echo "Unknown"
done | sort | uniq

How it works: #

• shopt -s globstar lets **/*.tif match all TIFF files recursively (way more reliable than parsing ls output)
• grep -o 'PROJCS\["[^"]*"\]' isolates the human-readable projection name string
• sed cleans up the output to remove the PROJCS[" and trailing " clutter
• sort | uniq ensures we only show distinct, non-duplicate projections

2. Verify Consistent NoData Values Across All TIFF Files #

To check if every TIFF shares the same NoData value, we'll collect all NoData values, deduplicate them, and validate the count. Here's the script:

#!/bin/bash
basepath=/home/rose/Desktop/GreatExtentDSMnodatacleaned # Update your root directory
shopt -s globstar

echo "=== Checking NoData Value Consistency ==="
cd "$basepath"
# Collect all NoData values (handling files with no NoData defined)
nodata_values=$(for f in **/*.tif; do
  gdalinfo "$f" | grep -o 'NoData Value\=[-0-9]*' | sed 's/NoData Value\=//' || echo "None"
done | sort | uniq)

# Count unique NoData values
unique_count=$(echo "$nodata_values" | wc -l)

if [ "$unique_count" -eq 1 ]; then
  echo "✅ All TIFF files have the same NoData value: $(echo "$nodata_values" | head -n1)"
else
  echo "❌ Found $unique_count distinct NoData values:"
  echo "$nodata_values"
fi

How it works: #

• We first gather all NoData values (or mark files without one as "None")
• sort | uniq reduces the list to only unique entries
• We count the unique entries: if only one exists, all files are consistent; otherwise, we list the differences clearly

Combined Script (Do Both Tasks at Once) #

If you want to run both checks in a single go, use this combined script:

#!/bin/bash
basepath=/home/rose/Desktop/GreatExtentDSMnodatacleaned # Update your root directory
shopt -s globstar

cd "$basepath"

echo "=== Unique Projections ==="
for f in **/*.tif; do
  gdalinfo "$f" | grep -o 'PROJCS\["[^"]*"\]' | sed 's/PROJCS\[//; s/"//g' || echo "Unknown"
done | sort | uniq

echo -e "\n=== NoData Value Consistency ==="
nodata_values=$(for f in **/*.tif; do
  gdalinfo "$f" | grep -o 'NoData Value\=[-0-9]*' | sed 's/NoData Value\=//' || echo "None"
done | sort | uniq)

unique_count=$(echo "$nodata_values" | wc -l)
if [ "$unique_count" -eq 1 ]; then
  echo "✅ All TIFF files have the same NoData value: $(echo "$nodata_values" | head -n1)"
else
  echo "❌ Found $unique_count distinct NoData values:"
  echo "$nodata_values"
fi

Quick Notes: #

• Ensure GDAL is installed (gdalinfo needs to be available in your system PATH)
• shopt -s globstar requires Bash 4.0 or newer (standard on most modern Linux/macOS systems)
• We replaced your original dir_list approach with Bash recursive globbing to avoid common pitfalls of parsing ls output

内容的提问来源于stack exchange，提问作者Rose