iv | Table of Contents
2.7 Saving Output from the ls Command 35
2.8 Sending Both Output and Error Messages to Different Files 37
2.9 Sending Both Output and Error Messages to the Same File 37
2.10 Appending Rather Than Clobbering Output 39
2.11 Using Just the Beginning or End of a File 39
2.12 Skipping a Header in a File 40
2.13 Throwing Output Away 41
2.14 Saving or Grouping Output from Several Commands 41
2.15 Connecting Two Programs by Using Output As Input 43
2.16 Saving a Copy of Output Even While Using It As Input 44
2.17 Connecting Two Programs by Using Output As Arguments 46
2.18 Using Multiple Redirects on One Line 47
2.19 Saving Output When Redirect Doesn’t Seem to Work 48
2.20 Swapping STDERR and STDOUT 50
2.21 Keeping Files Safe from Accidental Overwriting 52
2.22 Clobbering a File on Purpose 53
3. Standard Input
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55
3.1 Getting Input from a File 55
3.2 Keeping Your Data with Your Script 56
3.3 Preventing Weird Behavior in a Here-Document 57
3.4 Indenting Here-Documents 59
3.5 Getting User Input 60
3.6 Getting Yes or No Input 61
3.7 Selecting from a List of Options 64
3.8 Prompting for a Password 65
4. Executing Commands
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67
4.1 Running Any Executable 67
4.2 Telling If a Command Succeeded or Not 69
4.3 Running Several Commands in Sequence 71
4.4 Running Several Commands All at Once 72
4.5 Deciding Whether a Command Succeeds 74
4.6 Using Fewer if Statements 75
4.7 Running Long Jobs Unattended 76
4.8 Displaying Error Messages When Failures Occur 77
4.9 Running Commands from a Variable 78
4.10 Running All Scripts in a Directory 79
