From b7ce018c3a2615ce9ae9f819fdd5f2a9e8379dcf Mon Sep 17 00:00:00 2001 From: lkxed Date: Tue, 24 May 2022 23:50:10 +0800 Subject: [PATCH] =?UTF-8?q?[=E6=89=8B=E5=8A=A8=E9=80=89=E9=A2=98][tech]:?= =?UTF-8?q?=2020220524=20pdfgrep-=20Use=20Grep=20Like=20Search=20on=20PDF?= =?UTF-8?q?=20Files=20in=20Linux=20Command=20Line.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...arch on PDF Files in Linux Command Line.md | 234 ++++++++++++++++++ 1 file changed, 234 insertions(+) create mode 100644 sources/tech/20220524 pdfgrep- Use Grep Like Search on PDF Files in Linux Command Line.md diff --git a/sources/tech/20220524 pdfgrep- Use Grep Like Search on PDF Files in Linux Command Line.md b/sources/tech/20220524 pdfgrep- Use Grep Like Search on PDF Files in Linux Command Line.md new file mode 100644 index 0000000000..1dcbd177c6 --- /dev/null +++ b/sources/tech/20220524 pdfgrep- Use Grep Like Search on PDF Files in Linux Command Line.md @@ -0,0 +1,234 @@ +[#]: subject: "pdfgrep: Use Grep Like Search on PDF Files in Linux Command Line" +[#]: via: "https://itsfoss.com/pdfgrep/" +[#]: author: "Pratham Patel https://itsfoss.com/author/pratham/" +[#]: collector: "lkxed" +[#]: translator: " " +[#]: reviewer: " " +[#]: publisher: " " +[#]: url: " " + +pdfgrep: Use Grep Like Search on PDF Files in Linux Command Line +====== + +Even if you use the Linux command line moderately, you must have come across the [grep command][1]. + +Grep is used to search for a pattern in a text file. It can do crazy powerful things, like search for new lines, search for lines where there are no uppercase characters, search for lines where the initial character is a number, and much, much more. Check out some [common grep command examples][2] if you are interested. + +But grep works only on plain text files. It won’t work on PDF files because they are binary files. + +This is where pdfgrep comes into the picture. It works like grep for PDF files. Let us have a look at that. + +### Meet pdfgrep: grep like regex search for PDF files + +[pdfgrep][3] tries to be compatible with GNU Grep, where it makes sense. Several of your favorite grep options are supported (such as -r, -i, -n or -c). You can use to search for text inside the contents of PDF files. + +Though it doesn’t come pre-installed like grep, it is available in the repositories of most Linux distributions. + +You can use your distribution’s [package manager][4] to install this awesome tool. + +For users of Ubuntu and Debian-based distributions, use the apt command: + +``` +sudo apt install pdfgrep +``` + +For Red Hat and Fedora, you can use the dnf command: + +``` +sudo dnf install pdfgrep +``` + +Btw, do you run Arch? You can [use the pacman command][5]: + +``` +sudo pacman -S pdfgrep +``` + +### Using pdfgrep command + +Now that pdfgrep is installed let me show you how to use it in most common scenarios. + +If you have any experience with grep, then most of the options will feel familiar to you. + +To demonstrate, I will be using [The Linux Command Line][6] PDF book, written by William Shotts. It’s one of the [few Linux books that are legally available for free][7]. + +The syntax for pdfgrep is as follows: + +``` +pdfgrep [PATTERN] [FILE.pdf] +``` + +#### Normal search + +Let’s try doing a basic search for the text ‘xdg’ in the PDF file. + +``` +pdfgrep xdg TLCL-19.01.pdf +``` + +![simple search using pdfgrep][8] + +This resulted in only one match… But a match nonetheless! + +#### Case insensitive search + +Most of the time, the term ‘xdg’ is used with capitalized alphabetical characters. So, let’s try doing a case-insensitive search. For a case insensitive search, I will use the –ignore-case option. + +You can also use the shorter alternative, which is -i. + +``` +pdfgrep --ignore-case xdg TLCL-19.01.pdf +``` + +![case insensitive search using pdfgrep][9] + +As you can see, I got more matches after turning on case insensitive searching. + +#### Get a count of all matches + +Sometimes, the user wants to know how many matches were found of the word. Let’s see how many times the word ‘Linux’ is mentioned (with case insensitive matching). + +The option to use in this scenario is –count (or -c for short). + +``` +pdfgrep --ignore-case linux TLCL-19.01.pdf --count +``` + +![getting a count of matches using pdfgrep][10] + +Woah! Linux was mentioned 1200 times in this book… That was unexpected. + +#### Show page number + +Regular text files are giant monolithic files. There are no pages. But a PDF file has pages. So, you can see where the pattern was found and on which page. Use the –page-number option to show the page number where the pattern was matched. You can also use the `-n` option as a shorter alternative. + +Let us see how it works with an example. I want to see the pages where the word ‘awk’ matches. I added a space at the end of the pattern to prevent matching with words like ‘awkward’, getting unintentional matches would be *awkward*. Instead of escaping space with a backslash, you can also enclose it in single quotes ‘awk ‘. + +``` +pdfgrep --page-number --ignore-case awk\ TLCL-19.01.pdf +``` + +![show which pattern was found on which page using pdfgrep][11] + +The word ‘awk’ was found twice on page number 333, once on page 515 and once again on page 543 in the PDF file. + +#### Show match count per page + +Do you want to know how many matches were found on which page instead of showing the matches themselves? If you said yes, well it is your lucky day! + +Using the –page-count option does exactly that. As a shorter alternative, you use the -p option. When you provide this option to pdfgrep, it is assumed that you requested `-n` as well. + +Let’s take a look at how the output looks. For this example, I will see where the [ln command][12] is used in the book. + +``` +pdfgrep --page-count ln\ TLCL-19.01.pdf +``` + +![show which page has how many matches using pdfgrep][13] + +The output is in the form of ‘page number: matches’. This means, on page number 4, the command (or rather “pattern”) was found only once. But on page number 57, pdfgrep found 4 matches. + +#### Get some context + +When the number of matches found is quite big, it is nice to have some context. For that, pdfgrep provides some options. + +* –after-context NUM: Print NUM of lines that come after the matching lines (or use `-A`) +* –before-context NUM: Print NUM of lines that are before the matching lines (or use `-B`) +* –context NUM: Print NUM of lines that are before and come after the matching lines (or use `-C`) + +Let’s find ‘XDG’ in the PDF file, but this time, with a little more context ( ͡❛ ͜ʖ ͡❛) + +**Context after matches** + +Using the –after-context option along with a number, I can see which lines come after the line(s) that match. Below is an example of how it looks. + +``` +pdfgrep --after-context 2 XDG TLCL-19.01.pdf +``` + +![using '--after-context' option in pdfgrep][14] + +**Context before matches** + +Same thing can be done for scenarios when you need to know what lines are present before the line that matches. In that case, use the –before-context option, along with a number. Below is an example demonstrating usage of this option. + +``` +pdfgrep --before-context 2 XDG TLCL-19.01.pdf +``` + +![using '--before-context' option in pdfgrep][15] + +**Context around matches** + +If you want to see which lines are present before and come after the line that matched, use the –context option and also provide a number. Below is an example. + +``` +pdfgrep --context 2 XDG TLCL-19.01.pdf +``` + +![using '--context' option in pdfgrep][16] + +#### Caching + +A PDF file consists of images as well as text. When you have a large PDF file, it might take some time to skip other media, extract text and then “grep” it. Doing it often and waiting every time can get frustrating. + +For that reason, the –cache option exists. It caches the rendered text to speed up grep-ing. This is especially noticeable on large files. + +``` +pdfgrep --cache --ignore-case grep TLCL-19.01.pdf +``` + +![getting faster results using the '--cache' option][17] + +While not the be-all and end-all, I carried out a search 4 times. Twice with cache enable and twice without cache enable. To show the speed difference, I used the time command. Look closely at the time indicated by ‘real’ value. + +As you can see, the commands that include –cache option were completed faster than the ones that didn’t include it. + +Additionally, I suppressed the output using the –quiet option for faster completion. + +#### Password protected PDF files + +Yes, pdfgrep supports grep-ing even password-protected files. All you have to do is use the –password option, followed by the password. + +I do not have a password-protected file to demonstrate with, but you can use this option in the following manner: + +``` +pdfgrep --password [PASSWORD] [PATTERN] [FILE.pdf] +``` + +### Conclusion + +pdfgrep is a very handy tool if you are dealing with PDF files and want the functionality of ‘grep’, but for PDF files. A reason why I like pdfgrep is that it tries to be compatible with GNU Grep. + +Give it a try and let me know what you think of pdfgrep. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/pdfgrep/ + +作者：[Pratham Patel][a] +选题：[lkxed][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/pratham/ +[b]: https://github.com/lkxed +[1]: https://linuxhandbook.com/what-is-grep/ +[2]: https://linuxhandbook.com/grep-command-examples/ +[3]: https://pdfgrep.org/ +[4]: https://itsfoss.com/package-manager/ +[5]: https://itsfoss.com/pacman-command/ +[6]: https://www.linuxcommand.org/tlcl.php +[7]: https://itsfoss.com/learn-linux-for-free/ +[8]: https://itsfoss.com/wp-content/uploads/2022/05/01_pdfgrep_normal_search-1-800x308.webp +[9]: https://itsfoss.com/wp-content/uploads/2022/05/02_pdfgrep_case_insensitive-800x413.webp +[10]: https://itsfoss.com/wp-content/uploads/2022/05/03_pdfgrep_count-800x353.webp +[11]: https://itsfoss.com/wp-content/uploads/2022/05/04_pdfgrep_page_number-800x346.webp +[12]: https://linuxhandbook.com/ln-command/ +[13]: https://itsfoss.com/wp-content/uploads/2022/05/05_pdfgrep_pg_count-800x280.webp +[14]: https://itsfoss.com/wp-content/uploads/2022/05/06_pdfgrep_after_context-800x340.webp +[15]: https://itsfoss.com/wp-content/uploads/2022/05/07_pdfgrep_before_context-800x356.webp +[16]: https://itsfoss.com/wp-content/uploads/2022/05/08_pdfgrep_context-800x453.webp +[17]: https://itsfoss.com/wp-content/uploads/2022/05/09_pdfgrep_cache-800x575.webp