Manipulation of text by programs, scripts, etc.

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228
votes
5answers
82k views

Why is printf better than echo?

I have heard that printf is better than echo. I can recall only one instance from my experience where I had to use printf because echo didn't work for feeding some text into some program on RHEL 5.8 ...
45
votes
3answers
4k views

Why is using a shell loop to process text considered bad practice?

Is using a while loop to process text generally considered bad practice in POSIX shells? As Stéphane Chazelas pointed out, some of the reasons for not using shell loop are conceptual, reliability, ...
48
votes
4answers
26k views

Why is `while IFS= read` used so often, instead of `IFS=; while read..`?

It seems that normal practice would put the setting of IFS outside the while loop in order to not repeat setting it for each iteration... Is this just a habitual "monkey see, monkey do" style, as it ...
104
votes
3answers
218k views

How can I replace a string in a file(s)?

Replacing strings in files based on certain search criteria is a very common task. How can I replace string foo with bar in all files in the current directory? do the same recursively for sub ...
49
votes
9answers
66k views

Looping through files with spaces in the names?

I wrote the following script to diff the outputs of two directores with all the same files in them as such: #!/bin/bash for file in `find . -name "*.csv"` do echo "file = $file"; diff ...
22
votes
6answers
14k views

Removing control chars (including console codes / colours) from script output

I can use the "script" command to record an interactive session at the command line. However, this includes all control characters and colour codes. I can remove control characters (like backspace) ...
29
votes
4answers
16k views

How can I make iconv replace the input file with the converted output?

I have a bash script which enumerates through every *.php file in a directory and applies iconv to it. This gets output in STDOUT. Since adding the -o parameter ( in my experience ) actually writes ...
31
votes
8answers
7k views

Is there a way to modify a file in-place?

I have a fairly large file (35Gb), and I would like to filter this file in situ (i.e. I don't have enough disk space for another file), specifically I want to grep and ignore some patterns — is there ...
24
votes
11answers
12k views

Is there a robust command line tool for processing csv files?

I work with CSV files and sometimes need to quickly check the contents of a row or column from the command line. In many cases cut, head, tail, and friends will do the job; however, cut cannot easily ...
71
votes
12answers
38k views

how do you sort du output by size?

How do you sort du -sh /dir/* by size? I read one site that said use | sort -n but that's obviously not right. Here's an example that is wrong. [~]# du -sh /var/* | sort -n 0 /var/mail 1.2M ...
7
votes
5answers
12k views

Transposing rows and columns

I have a file with the lines like below. title1:A1 title2:A2 title3:A3 title4:A4 title5:A5 title1:B1 title2:B2 title3:B3 title4:B4 title5:B5 title1:C1 title2:C2 title3:C3 title4:C4 title5:C5 ...
51
votes
6answers
36k views

How to remove duplicate lines inside a text file?

A huge (up to 2 GiB) text file of mine contains about 100 exact duplicates of every line in it (useless in my case, as the file is a CSV-like data table). What I need is to remove all the repetitions ...
7
votes
2answers
2k views

In `while IFS= read..`, why does IFS have no effect?

I might have something absolutely wrong, but it looks convincing to me, that setting IFS as one of the commands in the pre-do/done list has absolutely no effect. The outer IFS (outside the while ...
15
votes
7answers
2k views

How can I prepend a tag to the beginning of several files?

I need to add PHP tags surrounding a file. It's easy to append them using find . -exec echo "?>" >> '{}' \; but how can I prepend the tag <?php?
12
votes
5answers
17k views

Remove comma between the quotes only in a comma delimited file

I have a input file delimited with commas (,). There are some fields enclosed in double quotes that are having a comma in them. Here is the sample row 123,"ABC, DEV 23",345,534.202,NAME I need to ...
10
votes
5answers
708 views

What's the best way to take a segment out of a text file?

What's a good way of extracting say, lines 20 -45 out of a huge text file. Non-interactively of course!
5
votes
3answers
1k views

Insert text from file inline after matching pattern in another file

I'm trying to take the contents of a file and insert it after a matching pattern in another file using sed. My question is very similar to this question, but I wish to insert the contents of a file ...
11
votes
4answers
20k views

Text between two tags

I wanna retrieve whatever is between these two tags – <tr> </tr> – from an html doc. Now I don't have any specific html requirements that would warrant for an html parser. I just plain ...
38
votes
9answers
8k views

Linux tools to treat files as sets and perform set operations on them

Does anyone know of any linux tool specifically designed to treat files as sets and perform set operations on them? Like difference, intersection, etc?
9
votes
5answers
3k views

Why does shell Command Substitution gobble up a trailing newline char?

As per the following example, and as in my recent question In bash, where has the trailing newline char gone?, I want to know "why" it happens x="$(echo -ne "a\nb\n")" ; echo -n "$x" | xxd -p # ...
3
votes
3answers
12k views

compare two columns of different files and print if it matches

I am using solaris 10 and Grep options involving -f doesnt work . I have two pipe separated files: file1: abc|123|BNY|apple| cab|234|cyx|orange| def|kumar|pki|bird| file 2 : abc|123| ...
10
votes
5answers
8k views

How do I recursively grep through compressed archives?

I'm trying to find out what modules use Test::Version in cpan. So I've used minicpan to mirror it. My problem is that I need to iterate through the archives that are downloaded, and grep the files ...
3
votes
4answers
287 views

Identifying genes from a list of genes

I have a gene list file. Some thing like this SWT21 SSA1 NRP1 EFB1 TFC3 MDM10 I have another file which also contains the names of these genes in my list along with other ...
28
votes
12answers
9k views

A standard tool to convert a byte-count into human KiB MiB etc; like du, ls1

Is there a standard tool which converts an integer count of Bytes into a human-readable count of the largest possible unit-size, while keeping the numeric value between 1.00 and 1023.99 ? I have my ...
21
votes
4answers
10k views

How to get only the unique results without having to sort data?

$ cat data.txt aaaaaa aaaaaa cccccc aaaaaa aaaaaa bbbbbb $ cat data.txt | uniq aaaaaa cccccc aaaaaa bbbbbb $ cat data.txt | sort | uniq aaaaaa bbbbbb cccccc $ The result that I need is to display ...
20
votes
1answer
1k views

How to implement a horizontal cat? [duplicate]

Standard cat concatenates files line by line (row by row, if you will). I find myself needing a horizontal cat command more and more often recently; i.e. a command that takes a list of files and ...
4
votes
3answers
4k views

How to bulk convert all the file in a file system branch between Unix and Windows line break format?

Everybody knows :-) that in Windows plain text files lines are terminated with CR+LF, and in Unix&Linux - with LF only. How can I quickly convert all my source code files from one format to ...
3
votes
4answers
2k views

Convert output of tree command to json format

Is there a convenient way to convert the output of the *nix command "tree" to JSON format? Edit: I think I didn't describe my problem well enough. My goal is to convert something like: . |-- dir1 | ...
5
votes
2answers
7k views

Show only text between 2 matching pattern

I'm going to submit form using cURL, where some of the contents is come from other file, selected using sed If param1 is line matching pattern from other file using sed, below command will works ...
3
votes
4answers
489 views

Shell script or command to Strip text and Binary files excerpts from large Log Files

I need to remove a large binary file (PDF file) from a large log file which is generated daily.This is seriously hogging space on our servers.I need to remove the large PDF from the logs to make the ...
53
votes
4answers
41k views

Can grep output only specified groupings that match?

Say I have a file: # file: 'test.txt' foobar bash 1 bash foobar happy foobar I only want to know what words appear after "foobar", so I can use this regex: "foobar \(\w\+\)" The parenthesis ...
14
votes
14answers
4k views

How to read an IP address backwards?

If we have this string (IP address): 192.168.1.1 How can I derive the (DNS reverse record form) from this string, so it will be shown like 1.1.168.192.in-addr.arpa using a shell script?
8
votes
2answers
17k views

How to cut (select) a field from text line counting from the end?

I know how to select a field from a line using the cut command. For instance, given the following data: a,b,c,d,e f,g,h,i,j k,l,m,n,o This command: cut -d, -f2 # returns the second field of the ...
5
votes
3answers
1k views

Fast way to build a test file with every second listed in YYYY-mm-dd HH:MM:SS format

I want to create a large test file with lines containg dates listed by the second, but my method is taking inordinately long... (or at least, that's how it feels :) ... 43 minutes to create only ...
13
votes
5answers
565 views

non-line-oriented tool for string replacement?

I recently asked a question about how to remove the newline character if it occurs after another specific character. Unix text-processing tools are very powerful, but almost all of them deal with ...
6
votes
3answers
179 views

How to print a line if that line or the next line do not contain a particular string

Input.txt: 8B0C remove 8B0D remove 8B0E remove 8B0F 8B10 remove 8B14 remove 8B15 remove 8B16 remove 8B17 remove 8AC0 8AC1 ...
3
votes
4answers
401 views

How to use sed command to modify a file's entry line by line in shell script?

This is my file1: #$BQ #{ VOL @home } #database daba #relation tcdeatid #copy 1 #{ version 0 } #opendb #clear #.lruno := 72 #.infno := 1 #.tid.noel := 101 #.tid.info ...
7
votes
5answers
33k views

Remove last character from line

I want to remove last character from a line: [root@ozzesh ~]#df -h | awk '{ print $5 }' Use% 22% 1% 1% 59% 51% 63% 5% Expected result: Use 22 1 1 59 51 63 5
5
votes
7answers
666 views

Turn list into single line with delimiter

I have to take a list (loads) of IP addresses in this format: 134.27.128.0 111.245.48.0 109.21.244.0 and turn them into this format with a pipe in-between (IPs made up) 134.27.128.0 | ...
5
votes
2answers
2k views

Remove all lines in file A which contain the strings in file B

I have a CSV file users.csv with a list of userNames, userIDs, and other data: username, userid, sidebar_side, sidebar_colour "John Lennon", 90123412, "left", "blue" "Paul McCartny", 30923833, ...
4
votes
3answers
232 views

Merge files using zipper method / late merge

I am searching for a nice method of merging two or more files line by line using the zipper method (also called late merge). Assuming we have three files, the result should look like this: line1 ...
2
votes
2answers
103 views

match first column of file a with paragraphs of file b

I have 2 files. The first, fileA looks like TCONS_00000066 XLOC_000030 - u q1:XLOC_000030|TCONS_00000066|0|0.000000|0.000000|0.000000|0.000000|- TCONS_00000130 XLOC_000057 - ...
1
vote
1answer
106 views

How to nest global matches with sed?

If I do: sed 's/match/replace/g' I know that sed will substitute replace for every occurrence of match on a line. But what if...? echo "match <please dont match this?>" | sed ...
0
votes
2answers
74 views

put data in columns

I am trying to put this output in columns can anyone help? Routeur 2 ==> 89.89.156.112 If_Name :vRtrIfName.1.1 :vRtrIfName.1.2 Routeur 2 ==> 89.89.156.112 If_index 546 789 Routeur 2 ==> ...
14
votes
8answers
9k views

How can I print lines from file backwards (without using “tac”)?

I want to print lines from a file backwards without using tac command. Is there any other solution to do such thing with bash?
3
votes
2answers
195 views

Merging files by rows

Is it possible to copy the whole rows of File1 in a new File3 following the instruction given by File2 by using a simple bash script using sed or awk? File1: /*two or more columns*/ AC 456324 DC ...
3
votes
2answers
119 views

Extract information from a text file

I have a text file, i want to search for tags such as the following: <category="SpecificDisease">Type II human complement C2 deficiency</category> <category="Modifier">Huntington ...
2
votes
2answers
79 views

Search and Replace question

I need to find all occurrences of AAsomeArbitraryStringBB and replace it with CCsomeArbitraryStringDD. So AAHelloBB Text AAByeByeBB becomes CCHelloDD Text CCByeByeDD. It's important to note ...
1
vote
3answers
177 views

Find records present in file 1 also in both file 2 and file 3

I have three files file1.txt, file2.txt, file3.txt and they are of same format. I want to select records from file1.txt which are present in both file2.txt and file3.txt based on column 2 and column ...
71
votes
11answers
77k views

How to add a newline to the end of a file?

Using version control systems I get annoyed at the noise when the diff says No newline at end of file. So I was wondering: How to add a newline at the end of a file to get rid off those messages?