String manipulation: extracting a part of a string, text replacement, formatting to a given width, etc.

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11
votes
3answers
353 views

Get all possible combinations of a word in lower/uppercase letters

I want to write a bash script to print all possible lower and upper case permutations of a certain word, e.g. harley: harley harleY harlEy harLey ... HARLey HARLEy HARLEY My naive solution is to ...
10
votes
5answers
2k views

Pattern matching on path names in bash

I want to act on a list of subdirectories in a directory. Consider: for x in x86-headers/*/C/populate.sh; do echo $x; done This gives x86-headers/elf/C/populate.sh x86-headers/gl/C/populate.sh ...
9
votes
4answers
36k views

Splitting string by the first occurrence of a delimiter

I have a string in the next format id;some text here with possible ; inside and want to split it to 2 strings by first occurrence of the ;. So, it should be: id and some text here with possible ; ...
9
votes
6answers
7k views

How can I test if a variable is empty or contains only spaces?

The following bash syntax verifies if param isn't empty: [[ ! -z $param ]] For example: param="" [[ ! -z $param ]] && echo "I am not zero" No output and its fine. But when param ...
8
votes
4answers
2k views

How do I find the overlap of two strings in bash? [closed]

I have two strings. For the sake of the example they are set like this: string1="test toast" string2="test test" What I want is to find the overlap starting at the beginning of the strings. With ...
8
votes
3answers
10k views

Bash - test for newline?

In various places around the web I've found: \015 \012 \x0a - hex \n \r all as synonyms for various newlines / carriage returns... But in this small script I cannot recognise when I come across a ...
7
votes
3answers
1k views

How to remove a specific character in a string but only if there are no numbers in that line in Linux

I've been stumped with this seemingly simple-to-fix problem.. well, for a while. Here's example output from the file I need to edit: $cat file George Washington Geneva Convention 123,281,029 USD ...
7
votes
7answers
2k views

Bash - Continuous String Manipulation

#!/bin/bash FILE="$(basename "$1")" FILE="${FILE/%.jpeg/.jpg}" Is there anyway to glue these two lines together into a one-liner?
7
votes
7answers
6k views

How to check if $PWD is a subdirectory of a given path

E.g. check if $PWD is a subdirectory of /home. In other words I'm searching for a bash string operation to check if one string starts with another.
6
votes
4answers
30k views

how to concatenate strings in bash?

I need to concatenate 2 strings in bash, so that: string1=hello string2=world mystring=string1+string2 echo mystring should produce helloworld
6
votes
6answers
11k views

Delete the last character of a string using string manipulation in shell script

I would like to delete the last character of a string, I tried this little script : #! /bin/sh t="lkj" t=${t:-2} echo $t but it prints "lkj", what I am doing wrong? Thank you in advance!
6
votes
2answers
3k views

grep surrounding characters of a match

I'm looking to do a find and replace within a giant database dump, and it's not doing what I think should happen. I'd like to grep for my target string in the file, and then see the surrounding 8 ...
6
votes
5answers
297 views

Number of characters in a shell command's output

I am writing a script which needs to calculate the number of characters in a command's output in a single step. For example, using the command readlink -f /etc/fstab should return 10 because the ...
6
votes
2answers
220 views

Piping bash string manipulation

I've read some other piping bash string manipulation questions but they seem to be specialized applications. Essentially, is there a way to do the below simpler? instead of $ string='hello world'; ...
6
votes
2answers
7k views

Extracting a string, according to a pattern, in a bash script

In bash, suppose that I have a string strname: strname="ph7go04325r" I would like to extract the characters between the first "3" character and the last "r" character in strname, saving the result ...
6
votes
1answer
10k views

bash - how to uppercase the command line argument?

I searched SO and found that to uppercase a string following would work str="Some string" echo ${str^^} But I tried to do a similar thing on a command-line argument, which gave me the following ...
6
votes
6answers
7k views

bash find lines starting with string

I have a bunch of files and I want to find which one contains sequential lines starting with a certain string. For example for the following file : Aaaaaaaaaaaa Baaaaaaaaaaa Cxxxxxxxxx Cyyyyyyyyy ...
6
votes
3answers
3k views

How to defer variable expansion

I was wanting to initialize some strings at the top of my script with variables that have no yet been set, such as: str1='I went to ${PLACE} and saw ${EVENT}' str2='If you do ${ACTION} you will ...
5
votes
7answers
2k views

How to find a position of a character using grep?

I need to identify the postion of a character in string using grep command. Example, the string is RAMSITALSKHMAN|1223333. grep -n '[^a-zA-Z0-9\$\~\%\#\^]' How do I find the position of | in the ...
5
votes
6answers
12k views

bash - replace space with new line

How can I replace spaces with new lines on an input like: /path/to/file /path/to/file2 /path/to/file3 /path/to/file4 /path/to/file5 etc... To obtain the following: /path/to/file /path/to/file2 ...
5
votes
2answers
2k views

Utility to get binary representation from string?

Is there a simple utility like printf that'll give me a "binary representation", i.e. a string like "01010010", from an input string? It would need to support multi-byte encodings.
5
votes
1answer
199 views

Test -n gives unexpected result

I understand test -n <expression> to return false if the expression evaluates to a string length of greater than 0. Why then does the following happen? Macbook:~ echo ${#undeclared_variable} 0 ...
5
votes
3answers
4k views

Most common encoding for strings in C++ in Linux (and Unix?)

For creating a C++ program that is source code level portable between Windows and Linux and handles internationalization well, there are IMHO three main encodings to consider: The encoding of the ...
5
votes
6answers
11k views

How to split such a string into array in bash

I have problem with output of a program. I need to launch a command in bash and take its ouput (string) and split it to add new lines in certain places. The string looks like this: battery.charge: ...
5
votes
6answers
2k views

How to match exact string using `sed`? But not the part of it.?

I have a input file FILE1.TXT as below. 11 id1 12 13 AGE = 20 14 NAME = NAME1 15 16 id2 17 18 AGE = 30 19 NAME = NAME2 . . . 110 idXYZ 111 112 AGE = AGEXYZ 113 NAME = ...
5
votes
2answers
2k views

Splitting bash command line argument

Is this the best way to split up a colon separated bash command line argument? #!/bin/bash hostlist=`echo $1| awk '{split($0,Ip,":")} END{for (var in Ip) print Ip[var];}'` for host in $hostlist do ...
5
votes
2answers
1k views

Add thousands separator in a number

In python re.sub(r"(?<=.)(?=(?:...)+$)", ",", stroke ) To split a number by triplets, e.g.: echo 123456789 | python -c 'import sys;import re; print re.sub(r"(?<=.)(?=(?:...)+$)", ",", ...
5
votes
3answers
267 views

Replace multiple strings in a single pass

I'm looking for a way to replace placeholder strings in a template file with concrete values, with common Unix tools (bash, sed, awk, maybe perl). It is important that the replacement is done in a ...
5
votes
3answers
101 views

how do I set quotes around a variable so that the programs sees them as quote marks

I am trying to get quotes around a variable to make is just like I typed it in the terminal to get this script to work. it shows " quotes around the varibale " but still does not see it as quotes, as ...
5
votes
2answers
544 views

ls for cut -f string not working

I have a problem with feeding cut output to ls. This doesn't work: rep="S1_1000,0000-00-00c,0000-00-00d,0000-00-00e" ls tab_yeast/{`echo $rep | cut -f2- -d','`}*.tab.gz ls: cannot access ...
4
votes
4answers
281 views

How do I show the numeric character sequence of a string?

Is there a command either standalone or in vi or similar (can be gui) that will show me the numeric sequence of a string? Input: The cat hopped in a box. Output: T h e c a t h o p p e d ...
4
votes
5answers
258 views

Replace new line + 4x space to new line in stdout

I need join 2 lines into one in stdout - replace new line AND 4x space with one space but new line without space don't touch tcpdump -vvv ... -l | xyz this is output: 2014-06-06 AAA BBB ...
4
votes
4answers
159 views

Check if content of file has length X and contains only specific characters

Let's say, I have files that contain only one docker id: myid.id: 28fe2baadbe8da32ed0b99c69b11c01b2d141bc5b732b81e0960086de52fc891 I want to check if the content of my.id is exactly 64 characters ...
4
votes
3answers
3k views

Case-insensitive substring search in a shell script [closed]

I'm trying to create a script which runs a command and compares the output of that command to a certain string to see if it contains that substring, ignoring the case of the string needed to be ...
4
votes
3answers
160 views

Change case of n-th letter in a string

I want to change the case of the n-th letter of a string in BASH (or any other *nix tools, e.g. sed, awk, tr, etc). I know that you can change the case a whole string using: ${str,,} # to lowercase ...
4
votes
5answers
250 views

Add leading characters infront of string using printf or echo

How can I add leading characters to fill a string to a certain length? Assume I want to add zeroes infront of a string, if said string is shorter than 20 characters: printf '%020s\n' "$line" ...
4
votes
4answers
991 views

Replace whole line in a file from command-line

I have a text file which has some contents similar to this: # General information about the project. project = u'Py6S' copyright = u'2012, Robin Wilson' # The version info for the project you're ...
4
votes
4answers
458 views

extract every nth character from a string

I am trying to figure out a solution for this question. My approach to this problem so far is as below. Append all the characters together to make it a long string. After the above step, remove ...
4
votes
1answer
74 views

Length of argument inside a function of an sh script

I have a FreeBSD 9.3 RELEASE server and I am trying to write a shell script using sh. I am trying to get the length of a variable that is passed to a function in a shell script, like so: #!/bin/sh ...
4
votes
2answers
588 views

Convert MAC address to Link-local address with bash

How can I convert a Mac address into an ipv6 Link-Local address? you have to add fe80:: at the start and insert ff:fe in the middle furthermore all leading zeros must be stripped
4
votes
3answers
13k views

How to get the first word of a string?

When I 'echo *' I get the following output: file1 file2 file3 ... What I want is to pick out the first word. How can I proceed?
4
votes
2answers
128 views

Write variable containing large text with \n to a file with common shell interpreters. How do you do it?

Environment: linux shell or better, ash shell in busybox (example system: Openwrt). Given a string variable with large text "${a}" constructed in this way: for index in $(seq 1 40000); do #it is ...
4
votes
2answers
365 views

Replace very long string in files recursively

I have a very long and complex string in many files and I want to remove/replace it recursively. The string contains many slashes, backslashes and spaces and any kind of special signs. How do I do ...
4
votes
2answers
6k views

Bash : compare two strings with space

I am trying to write a bash script which run a command and compare the result with another string. #!/bin/bash -x STATUS=`/root/setup_ha show --password-file=/root/password | grep ">HA State" | ...
3
votes
7answers
227 views

get parts of string using shell script

I have one string as /ip/192.168.0.1/port/8080/ I want to get two separate variables which will contain port and IP like. 192.168.0.1 and 8080 as I know /ip/ and /port/ will be there always I ...
3
votes
2answers
319 views

grep on a variable

Lets say I have a variable line="This is where we select from a table." now I want to grep how many times does select occur in the sentence. grep -ci "select" $line I tried that, but it did not ...
3
votes
6answers
3k views

How to reverse a string made of digit in bash?

What is the best way to turn out digits in number? E.g. $ echo 123 | hook 321 $ echo 12358 | hook 85321
3
votes
3answers
2k views

How to capture error message from executed command?

I was tasked to create an automated server hardening script and one thing that they need is a report of all the output of each command executed. I want to store the error message inside a string and ...
3
votes
4answers
280 views

Command to remove a portion of JSON data from each line?

I have test.json file with different lengths of rows. Some fictitious example: { a: 123, b: sd, c: x45, d: 1, e: '' } { a: 5, b: bfgg, c: x4c, d: 31, e: '' } I want to cut the whole substring after ...
3
votes
2answers
178 views

Shell script to assign values from a lookup table is too slow

I'm trying to assign some variables from a lookup file with a shell script. I have something working but it seems unnecessary slow. Script: while read line do ...