Shell Script Help on file reading


Recommended Posts

Hi,

I need a little help on file reading. I have a file and its contents are like

123456789123456789123456789

987654321987654321987654321

231297301283120381290382133

Now I need script to format this file like

A B C D E F G H I J K L M

123 456 789 123 456 789 12 3 4 56 7 8 9

987 654 321 987 654 321 98 7 6 54 3 2 1

231 297 301 283 120 381 29 0 3 82 1 3 3

i.e the first line shows the differentiating columns and the rest of the lines following those columns.

Please help me on how this can be done.

Thank you.

Link to comment
https://www.neowin.net/forum/topic/1136228-shell-script-help-on-file-reading/
Share on other sites

Is the break down the same,

3-digits 3-digits 3-digits 3-digits 3-digits 3-digits 2-digits 1-digit 1-digit 2-digits 1-digit 1-digit?

This might be an awkward way about the problem but,

#! /bin/bash

for i in `cat filename.ext`;

do

echo ${i:0:2} ${i:3:6} ${i:7:9} ${i:10:12} ${i:13:15} ${i:16:18} ${i:19:20} ${i:21:21} ${i:22:22} ${i:23:24} ${i:25:25} ${i:26:26} >> outputfiles.ext

done;

Clearly not the cleanest way of doing it - P.s. I have not tested this as I am on an android phone lol

You are very close. This is exactly what I want. In simple terms, I want to break the characters and present them in a format like first three characters. then 4-6. then 7-12, then 8-9 and so on. The length of each line in the file remains the same and so I need to format it in different ways.

I tested your code, but the output is not coming according to the code. It would have been perfect otherwise.

Thank you :)

I tested your code, but the output is not coming according to the code. It would have been perfect otherwise.

Do you mean,

1: The wrong number of digits broke down? (Which is possible as I wrote that on an Andriod phone and I cannot see the whole block of code.)

2: The IFS the internal field separate is not triggering the line breaks? (Which is possible depending on where and what is used to create the file in the first place)

This is coming as output of your code

12 456789 891234567 23456789 56789 89

98 654321 219876543 87654321 54321 21

12 121112 123123124 12312412 12412 12

This is not consistent with the code. Your code has divided each line into 12 parts. Therefore the output should have been in 12 parts. The file has been created just by typing the lines to check how it can be broken up.

I would be interested in knowing what this is for LOL

I did the example from memory and I made a mistake in thinking is Variable:Start Reference:End Reference where in actuality it is Variable:Start Reference:Length

#

# YOUR EXAMPLE

#

[Tim.IT-8] ? cat example.txt

123456789123456789123456789

987654321987654321987654321

231297301283120381290382133

#

# SCRIPT

#

[Tim.IT-8] ? cat example.sh

#! /bin/bash

# VARIABLES

INPUTFILE=example.txt

OUTPUTFILE=example_completed.txt

# CLEAR THE SCREEN

clear

# PROCESS

for i in `cat $INPUTFILE`;

do

echo "${i:0:3} ${i:3:3} ${i:6:3} ${i:9:3} ${i:12:3} ${i:15:3} ${i:18:2} ${i:20:1} ${i:21:1} ${i:22:2} ${i:24:1} ${i:25:1} ${i:26:1}" >> $OUTPUTFILE;

done;

# CLEANUP

unset INPUTFILE;

unset OUTPUTFILE;

#

# RESULTS

#

[Tim.IT-8] ? cat example_completed.txt

123 456 789 123 456 789 12 3 4 56 7 8 9

987 654 321 987 654 321 98 7 6 54 3 2 1

231 297 301 283 120 381 29 0 3 82 1 3 3

#

# YOUR EXPECTATION

#

A B C D E F G H I J K L M

123 456 789 123 456 789 12 3 4 56 7 8 9

987 654 321 987 654 321 98 7 6 54 3 2 1

231 297 301 283 120 381 29 0 3 82 1 3 3

  • 2 months later...

Hi tim, sorry for the delayed response.

I checked your code and thanx a ton for this. It is now coming as expected. I also understood the code this time. I have a file where the lines are like

xyz12345	 12345    mprls   12345

Here the blank spaces are also character and every bit of it represents a format. e.g 1st 3 letters will represent something, 4 something else, 5-6, 7-9 and so on. It is for my own clarity, otherwise I have to debug the code manually where the debug file consists of thousands of such lines of equal width and the same format.

Thanx a lot for this. I will check this again on the raw file and if it can format the blank spaces as well.

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • Microsoft released Windows 11 KB5094149 / KB5095971 / KB5094156 Setup, Recovery updates by Sayan Sen Earlier this week Microsoft released its newest Patch Tuesday updates (KB5094126 / KB5093998 on Windows 11 and KB5094127 on Windows 10). Alongside those, Microsoft also released new dynamic updates. These Dynamic Update packages are meant to be applied to existing Windows images prior to their deployment. Dynamic Updates also help preserve Language Pack (LP) and Features on Demand (FODs) content during the upgrade process. VBScript, for example, is currently an FOD on Windows 11 24H2. This time both recovery and setup updates were released for Windows 11 as well as Windows 10. The company writes: "KB5095185: Safe OS Dynamic Update for Windows 11, version 26H1: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.28000.2269. KB5094149: Safe OS Dynamic Update for Windows 11, versions 24H2 and 25H2: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.26100.8655 KB5095971: Setup Dynamic Update for Windows 11, version 23H2: June 9, 2026 This update makes improvements to Windows setup binaries or any files that setup uses for feature updates in Windows 11, version 23H2. KB5094156: Safe OS Dynamic Update for Windows 11, version 23H2: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.22621.7219 KB5098815: Windows Recovery Environment update for Windows 10, version 21H2 and 22H2: June 9, 2026 This update automatically applies Safe OS Dynamic Update (KB5094154) to the Windows Recovery Environment (WinRE) on a running PC. The update installs improvements to Windows recovery features. KB5094154: Safe OS Dynamic Update for Windows 10, versions 21H2 and 22H2: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.19041.7417. KB5094153: Safe OS Dynamic Update for Windows 10, version 1809 and Windows Server 2019: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.17763.8880. KB5094152: Safe OS Dynamic Update for Windows 10, version 1607 and Windows Server 2016: June 9, 2026 This update makes improvements to the Windows recovery environment (WinRE). After installing this update, the WinRE version installed on the device should be 10.0.14393.9234." Microsoft notes that both the Recovery and Setup updates will be downloaded and installed automatically via the Windows Update channel.
    • Quantum Error Correction Validated in Nature: Microsoft and Quantinuum Log 800-Fold Improvement Two years after the original press-release announcement, independently peer-reviewed results published in Nature on June 10, 2026, have confirmed that Microsoft and Quantinuum achieved an 800-fold reduction in quantum error rates on real trapped-ion hardware — the largest gap between physical and logical error rates ever independently validated.    What Quantum Error Correction Actually Does — and Why Breaking Even Is Hard https://www.techtimes.com/articles/318329/20260613/quantum-error-correction-validated-nature-microsoft-quantinuum-log-800-fold-improvement.htm   Quantum Computing Wiring Bottleneck Cracked by HKU Silicon Carbide Chip at Qubit Temperature Engineers at the University of Hong Kong have built the first cryogenic control chip that operates at the same temperature as superconducting qubits — 10 millikelvin, or just one-hundredth of a degree above absolute zero — without generating the heat that has forced every competing approach to park its electronics hundreds of meters of cable away. https://www.techtimes.com/articles/318325/20260613/quantum-computing-wiring-bottleneck-cracked-hku-silicon-carbide-chip-qubit-temperature.htm  
    • RevPDF 4.5.0 by Razvan Serea RevPDF is a free, fully offline PDF editor for Windows, macOS, and Linux that lets you edit text and images directly inside PDF files — no internet connection, no account, and no cloud uploads required. Unlike bloated alternatives that demand subscriptions and constant connectivity, RevPDF fits in under 60MB on desktop while delivering a complete editing toolkit: annotate, redact, sign, compress, split, merge, convert, and reorganize pages, all processed locally on your device. Smart font matching ensures edited text blends seamlessly with the original, and multi-language support includes RTL scripts such as Arabic and Hebrew. Where most PDF editors force you to choose between features and simplicity, RevPDF manages both. You can build interactive forms from scratch with text fields, checkboxes, and dropdowns, permanently redact sensitive data before sharing, draw freehand on contracts and diagrams, and add custom watermarks — all without a single file leaving your machine. Edit Text and Images Directly Inside PDFs RevPDF supports true inline PDF editing — not just annotation layers on top of a document, but actual modification of existing text and images within the file. A smart font-matching engine identifies the font used in the original document and applies it automatically when you make edits, so changes blend naturally with the surrounding content. You can reposition elements, resize images, and update text across single pages or entire documents. RevPDF 4.5.0 release notes: This is one of the biggest updates to RevPDF yet. A lot of things people have been asking for are finally here. New Features Auto Redaction Permanently redact sensitive text and areas from your PDFs before sharing. Clean, irreversible, and fully offline. Comments, Links & Bookmarks Add comments for review, insert clickable links, and create bookmarks to jump around long documents without scrolling forever. Find & Replace Search across the whole document and replace text in one go. Long overdue. Split Pages Vertically or Horizontally Split any page down the middle, vertically or horizontally. Perfect for scanned books or double-page spreads. New Drawing Tools More tools for freehand drawing and markup, better for annotations, sketches, and detailed notes. Continuous Scrolling in Editor The editor now scrolls continuously through pages instead of jumping between them. Working through long documents is a lot smoother now. PDF Metadata Editor View and edit the metadata stored inside your PDFs, including title, author, subject, and keywords. Better Font Matching Text edits now blend in more naturally by doing a better job of matching the original font. Tabbed PDF Viewer Open multiple PDFs at once in tabs and switch between them without going back to the home screen. Add Links Insert hyperlinks anywhere in your PDF, to external URLs or to other pages within the document. Share & Print Shortcuts Share or print directly from the editing screen, home screen, and viewer. No extra steps. Minor Updates Paste images directly from clipboard into your PDF New image editing tools for more control over images inside documents Bug Fixes Fixed file saving issues on Windows and Linux Everything still works fully offline. No login, no cloud, no account. Your files stay on your device. Download: RevPDF 4.5.0 | 58.0 MB (Open Source) Links: RevPDF Home Page | Github | Screenshots 1 | 2 Get alerted to all of our Software updates on Twitter at @NeowinSoftware
    • Interesting. I'm not using a VPN with my phone. I tried though my home internet (Rogers) and my cellular internet (Telus) using their respective DNS servers and both trigger the dialog above.
    • Three days after Anthropic launched Claude Fable 5 as the most capable AI model it had ever released to the public, the United States government ordered it switched off — and now the company is refunding customers who paid to use a product that vanished almost overnight https://www.techtimes.com/articles/318342/20260613/us-government-pulls-anthropics-fable-5-offline-now-come-refunds-vanished-ai.htm  
  • Recent Achievements

    • Week One Done
      agatameier earned a badge
      Week One Done
    • One Month Later
      agatameier earned a badge
      One Month Later
    • Week One Done
      ssd21345 earned a badge
      Week One Done
    • Contributor
      MarkHughes4096 went up a rank
      Contributor
    • Dedicated
      jordanspringer earned a badge
      Dedicated
  • Popular Contributors

    1. 1
      +primortal
      507
    2. 2
      +Edouard
      175
    3. 3
      PsYcHoKiLLa
      139
    4. 4
      ATLien_0
      91
    5. 5
      Steven P.
      76
  • Tell a friend

    Love Neowin? Tell a friend!