Bash get last character of file. Read first line from latest file.

• Bash get last character of file. head and pipe with tail will be slow for a huge file.

  Bash get last character of file If I execute a command like tail -n 50 Skip to main content. Is there a way to do this? Try file -k. Replacing last number in IP address with 1 $ hostname -i | sed 's/. while IFS= read -r line do # Check the line length. For example, if `string` is “hello world”, then What i would like to accomplish is to take a file name let's say myfileRE. For example, you obtain the last line in a file with, tail -n1 file. The problem is that '--mkpath' does create a dir by means of a bash script without zenity but not bmo a bash script with zenity --file-selection. Then, print only the last elment in the array: # Print only the last element via bash array right-hand-side indexing syntax echo "${A_array[-1]}" # last element only Output: abc. #!/bin/sh for f in $(find . $--' your_file To quickly truncate the last character of a file you can use: truncate -s-1 file This will modify the file directly and avoid creating a copy of your large file. FOO="qwertzuiopasdfghjklyxcvbnm" I need to get qwertzuiop. This is because [[:blank:]]* and [^[:blank:]]* are boolean complements and - provided all characters in a string are complete - [[:blank:]]*U[^[:blank:]]* can describe any possible string in much the same way . sed '$ s/. NB: you may have issues if the final character is multi-byte, but a semi-colon isn't deleteing the last four characters of a name with bash. txt, I want this string to be split as . */\1/' sample. -Fcharacter class symbol inside that put underscore dot close the character class. Stack Overflow. *}" echo "extension: ${file##*. sed '$ s-. Processes Learn about For variety, a bash only solution. txt How can I remove the last 8 characters of each line? Expected output of data_list. Examples: The thing is, the number of "/" can differ. 3. How to print first word of first line and last word of last line in unix in a file. txt will tell you line terminators: It will output with CRLF line terminators for DOS/Windows line terminators. X:20234 214. string1=a. Note that the first and last number of characters can even be different: sed -e 's/^\(. Does The last character in a text file is a newline character, the delimiter of the last line. I would suggest sed like this:. $// function call executes on the endmost line of the file. head --bytes 10 will output the first ten characters, but head --bytes -10 will output everything except the last ten. If you do not use double quotes, basename will not work with path where there is space character: $ basename /home/foo/bar foo/bar. Now, how do I make an array containing just {SOME NUMBERS I I am using a Mac terminal (bash) and I have a file called data_list. length, -1) = "0" do something In englishif the last character in the string is 0 then Given a string file path such as /foo/fizzbuzz. *\(. get the offset of last _ to pos1 get the offset of last . txt that contains n lines as follows: aaabbbccc_7777. txt" echo "filename: ${file%. Here is a way using grep:. in It does this by deleting everything up to and including the last whitespace character on each line. Thus . How do I get the last word in each line with bash . /usr/bin/git -> git Print the last 7 characters in each string of the in_file: perl -lpe '$_ = substr $_, -7;' in_file > out_file Output: 1234567 1234567 123456 Note that if the input has less than 7 characters, it prints only the available number of characters. Then I want to get the last X characters of the string variable: #!/bin/bash someline="this is the last line content" echo I would like to get get the last character from all the lines, also last 3 characters. It's also empty if the last character is a null byte (in most shells), but text files don't have null bytes. Follow edited Aug 5, 2020 at 10:51. foobar bar bar foo foo bar bar foobar I would like to get get the last character from all the lines, also last 3 characters. Seaching for files is not searching for entries, under Un*x, Everything is a file, so under a path, you could find sockets, devices, fifos, and lot of other things which are not files. This asks truncate to reduce the size of the file by 1 . I have a simple script to automatically download Android firmware and decrypt it. Command substitution strips off a trailing newline, so $(tail -c 1 <) is empty if the last character of the file is a newline. I used cut but it splits as a,b,c and txt. I'll leave it to you to figure out how to The canonical tool for that would be sed. Follow answered Feb 12, 2018 at 10:03. The thing is, the number of "/" can differ. Sorry commented through my mobile. Follow edited Apr 20, 2015 at 16:58. I've succeeded in doing this but, purely out of curiosity, I'm wondering if there is a shorter, single command I can use. C++ Java PHP Python Kotlin Swift JavaScript Golang. %pattern trims off the shortest suffix Data read in from a text stream will necessarily compare equal to the data that were earlier written out to that stream only if: the data consist only of printing characters and the control characters horizontal tab and new-line; no new-line character is immediately preceded by space characters; and the last character is a new-line character sed 's/. If you want to remove a filename suffix but don't know or To answer the first line of your question which asks to "remove the last n characters from a string", you can use the substring extraction feature in Bash: A="123456" echo ${A:0:-2} # remove last 2 chars 1234 However, based on your examples you appear to want to remove all trailing commas, in which case you could use sed 's/,*$//'. Thanks. The files are formatted as coffee_{SOME NUMBERS I WANT}. Follow edited Jun 18, 2014 at 12:37. About; Products OverflowAI; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about You can index strings in Bash using ${var:index} and ${#var} to get the length of the string. , for 6 characters it only prints 6, and for an empty string input it prints empty string. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, . Improve this answer. Typically it counts lines, but it can be made to count characters/bytes instead. My current approach to extracting the last three characters of every line in a file or stream is to use sed to capture the last three characters in a group and replace the entire line You might commonly use this syntax with other characters to trim filenames: ${A##*/} removes all containing folders, if any, from the start of the path, e. Skip to main content . 27. 8k 6 6 gold badges 43 43 silver badges Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Visit the blog The issue with this solution is that if the file you're scanning is a shell script file then it will only filter the echo output rather than the actual file contents, try 1) creating a script file with a few simple echo commands; 2) pasting the full file path into the console and entering " | tail -1" at the end; notice that it will only output your last echo command's output rather than the All of those commands do what you are looking for, the awk command will just do the operation on the last line of the file so you do not need tail anymore, the said command will extract the last line of the file and store it in its pattern buffer, then replace everything that is not the first 2 chars by nothing and then print the pattern buffer (the 2 fist char of the last line), If you do have bash (it's available on most Linux distros and, even if your login shell is not bash, you should be able to run scripts with it), it's the much easier: firstchar=${name:0:1} For escaping the value so that it's not interpreted by the shell, you need to use: If you want to strictly remove THE LAST newline character from a file, use Perl: perl -pe 'chomp if eof' log. Is there a way to do the same via cut? cut string on last delimiter. I have a string that looks like this: GenFiltEff=7. cz. txt Note that if you are certain you have a trailing newline character you want to remove, you can use head from GNU coreutils to select everything except the last byte. I have a filename like a. grep -o '[^,]*$' Replace the comma for other delimiters. cat file | rev | cut -d" " -f1 | rev | tr -d ". It can be done fairly easily with tail and then string indexing in bash. log) but it doesn't seem to be writing new line characters at the end of each log entry. See original answer: To get last character in a string in Bash scripting, you can use parameter expansion and substring expansion as shown in the following expression. c string2=txt Basically I want to split filename and its extension. You will need to store the line in a variable using command-substitution, e. So if you know the string ends in a . Reading SO request: get the header (first 10 bytes) of a file and then in another section get everything except the first 10 bytes. Add a comment | 3 . (So if it does not explicitly mention any kind of line terminators then this means: "LF line terminators". Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their Using Bash, there’s also ${file%. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for I've found the way to only show the last line of a grep search : grep PATERN FILE_NAME | tail -1 I also find the way to make a grep search in multiple selected files : find . Result: this is the last line content line 4: Bad substitution What might be wrong here? Let's test it with a simple file consisting on just lines, two with just spaces and the last one also with tabs: $ cat -vet file hello $ bye $ ha^I $ # there is a tab here Remove just spaces: $ sed 's/ *$//' file | cat -vet - hello$ bye$ ha^I$ # tab is still here! Remove spaces and tabs: So instead, you'll need to use a single tool that can detect the last line, which is a more efficient approach anyway. [^,] is a character class that matches any character other than a comma. E. periket2000 periket2000. Skip to content TutorialKart. However, if you have a big file it should be more efficient to reverse the lines using tac and grep -m 1 to get the first match (that is, the last match in the original file). echo ${lastln:(-1)} How to split a stream (or a file) under bash. That's all. In pseudo code. Networking The building blocks for machine-to-machine communication Files Deep dive into working with Files on Linux. *stalled: //p' Detailed explanation:-n means not to print anything by default. 1. If rsync would create the new dir (the last word of the path-line), I could just select one I want to rename files by removing the last N characters For example I want to rename these files by removing the last 7 characters From: file. So a file with the text 'hello' will print 6 if you use echo etc, but if you use printf it will return the exact 5, because theres no I want to grep the second last or nth last character from each line of a file. Stack Exchange Network. * meaning any text, with an initial ^ to say that the match begins at the Remove the file name, leaving the path (delete shortest match after last /): echo ${MYVAR%/*} users/joebloggs Get just the file extension (remove all before last period): echo ${MYVAR##*. To access the last n characters of a string, we can use the parameter expansion syntax ${string: -n} in the Bash shell. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their head outputs only the beginning of a stream or file. txt nnhhaa_8888. before the end of line (= end of file) $, and changes it into nothing. If your input had ISO timestamps at the start of the line you could simply pipe it through sort to order them. txt Is this doable in a single How to retrieve the first 10 characters of a variable with Bash? FOO="qwertzuiopasdfghjklyxcvbnm" I need to get qwertzuiop. *stalled: matches the pattern you're looking for, plus any preceding text (. ) You can use bash string manipulation: $ foo=a-b-c-def-ghi $ echo "${foo%-*}" a-b-c-def The operators, # and % are on either side of $ on a QWERTY keyboard, which helps to remember how they modify the variable: #pattern trims off the shortest prefix matching "pattern". } example NOTE: To do two operations, you can't combine them, but have to assign to an intermediate variable. Examples: In bash I would like to extract part of many filenames and save that output to another file. ; ##pattern trims off the longest prefix matching "pattern". This syntax uses the “ operator to extract the substring of `string` that starts at the last occurrence of the delimiter character (`*`) and goes to the end of the string. *} to remove the extension: echo ${file%. 0. \{2\}\)$/\1 \2/' This would return the first 5 characters and last 2 characters of each line. $//' To remove the last character. To get exact character count of string, use printf, as opposed to echo, cat, or running wc -c directly on a file, because using echo, cat, etc will count a newline character, which will give you the amount of characters including the newline character. Note that GNU df (your -h is already a GNU extension, though not needed here) can also be told to only output the disk usage 2. In bash scripting, the cut command mainly extracts characters, bytes, and fields from the input string. $ is a regex that matches the last character in the file Note that you can use whatever separator you want instead of /, for example you can rewrite the expression:. blah. On the plus side it's This tutorial explains how to get the last N characters from a string in Bash, including several examples. How to remove first n character of multiple file names in mac. The easiest way to do so is by using the tail command, which allows you to display the last part of a given input. Get last 2 parts of lines. It is not possible using just cut. txt (. I want to cut the string on the last delimiter. if var1. 6k 22 22 gold badges 110 110 silver badges Another way of doing this in plain bash is making use of the rev command like this:. Viewed 151k times 33 . You would have to type the new dir at destination from zenity --file-selection, if it doesn't exist. I understand: How to split a file at specific point. -e is followed by a sed command. For instance: STRING="one two three four" N=3 Result: "three" What Bash command/script could do this? For example a file may contain stuff_C stuff_P things_C things_P stu_P_ff thi_P_ngs I only want to capture stuff_P & things_P sent to stdout. My script (see below) does successfully remove the last character of a path, but for some reason it also sometimes removes the last character even if it isn't "/". cz Vojtech Vitek - golang. XXX. answered Jun 18, 2014 at 11:20. *[[:space:]]//' data. Vojtech Vitek - golang. If long is shorter than two characters, short will be identical to it. That is, file="thisfile. * matches the rest of the line, because we want to replace the entire line, not just the capture group. Then I want to get the last X characters of the string variable: #!/bin/bash someline="this is the last line content" echo ${someline} somepart=${someline: -5} echo ${somepart} Run with: sh lastchars. txt ayqynbnbn_1122. It truncates a file by two bytes if the last two bytes are CR/LF, or by one byte if the last byte is LF. In this way, it completely takes Now, we want to get the last 3 characters gal from the above string. png 0 I am using this command to iterate over the text file and get last char. 092200e-01 Using bash, I would like to just get the number after the = character. Conveniently, sed offers a way of matching the last line. X:7249 [2200:XXXX:XXXX:XXX:XXXX:X Skip to main content. txt that contains multiple lines and store the content of the last line into a variable called "tag". I'm reading the last line of a file into a variable. Using “cut” Command. blah" pax> short="${long:0:2}" ; echo "${short}" US This will set short to be the first two characters of long. . In particular, one method included using rev in conjunction with cut. I am using following for loop workaround to get the desired output, but I guess cut command But to get the last 3 characters from $base there, the best I could do was the three-line name=${var##*/} ; base=${name%%. Explanation: NUMq will quit immediately when the line number is NUM. Either printing all lines but the last, or suppressing the last output line, will work: sed -n '$! p' sed '$ d' It will replace last char by X in each line, rewrite file filename. Peter Mortensen. ; The regular expression ^. I need to extract the characters before last colon : and also remove the square brackets [] in the last line. It replaces the last character (s) with an empty string. This approach will not work without the space. -name 'coffee*. If you can guarantee that the filenames will not contain funny characters I have an application that is logging to a plain text log file (myapp. The string slicing variable expansions here are handy. To get the last character you should just use -1 as the index since the negative indices count from the end of the string: The space after the colon (:) is REQUIRED. $/1/' Replacing 't' with 'z' $ echo "xyt" | sed 's/. $//' your_file First $ is to tell sed to match only last line; s is for "substitute", note the empty string between the two last /s. txt ooppaa_3454. *} ; lastpart=${base#${base%???}}. rtf that you want to remove, you can just use var2=${var%. It You can use sed:. Why *not* parse `ls` (and what to do instead)?). d will delete the line instead of printing it; this is inhibited on the last line Probably the most efficient method, if you're using the bash shell (and you appear to be, based on your comments), is to use the sub-string variant of parameter expansion:. I tried this : Do not parse the output of ls (see e. {0,5}) greedily matches any character up to 5 times, and creates a capture group. txt and return the new file name of myfile. b. to pos2 substring from _ offset to . In your case, it's added by echo which always adds one unless you use the -n option (with some implementations), or add a \c (with others, the standard ones, not the case of yours which seems to supports that non-standard -e). I'm not able to find how to do this in Linux. Skip to main content tail -c 1 outputs the last character (more precisely, the last byte) of its input. But in this specific case, you could also do: df -P | awk 'NR > 1 {print $5+0}' With the arithmetic expression ($5+0) we force awk to interpret the 5th field as a number, and anything after the number will be ignored. First of all, you remove the extension if any: name_no_ext=${file%. 2,398 1 1 gold badge 14 14 I'm trying to set a variable in an sh script to the last 3 characters of the base name of a file (by base name I mean without the path and without the suffix). I know that I can use ${file%. ” (dot) refers to any character and the last $ points to the end of the line. txt. sh. How do I do that using Bash? I tried cut, but I don't know how to specify the last field with -f. Loop through filenames and delete last n charaters. *} then, you get the last char: If you want to learn more about string manipulation in bash, go to section I'm reading the last line of a file into a variable. However I need to use correct decryption type of the file The -z option is to interpret the file as a single long string (newlines are embedded as \n), then s matches the single character . The extra two characters will always be two characters and so what i tried to do was: Get list of files in a directory in shell and in bash, 4 tips Some remarks. ×. If you are not sure the last character is name_no_ext=${file%. Modified 6 years, 10 months ago. *} outputs How to get last character from base file name? Ask Question Asked 3 years, 9 months ago. freqdist) That code will find all the coffee_{SOME NUMBERS I WANT}. } to get the extension alone. In Bash, you can get the last part of a string using the `${string*}` syntax. 31. pax> long="USCAGol. txt ayquabay_9999. 123 Going further: What makes this pattern so useful too is that it allows you to easily do the opposite too!: obtain all words except the last one, like this: Suppose I have the string 1:2:3:4:5 and I want to get its last field (5 in this case). sahaquiel sahaquiel. Use the substr( $0, start_character_position, original_string_length($0)-1 ) }' In Bash, I want to get the Nth word of a string hold by a variable. BTW, negative indices count from right, so "${1: -1}" is enough. bar, how would I use bash to extract just the fizzbuzz portion of said string? Skip to main content. This modifies the file in-place, rather than making a copy of the file and stripping the newline from the last line of the copy. freqdist file. How can I get the first extension of a filename in a shell script? 2. txt: aaabbbccc_ nnhhaa_ ayquabay_ ayqynbnbn_ ooppaa_ How can I understand if I am reading the last line of a file in bash? 117. freqdist. I want to read a text file called history. how to get last line first 2 character of a file in linux. You probably meant "how to remove the last character of the With sed on a file, the following would extract the last whitespace-separated field of each line: sed 's/^. So to get the file name without path or extension: If you qualify word to mean any sequence of 1 or more non-blank characters then the answer is definitely yes, and it is very simply done as well. Example: file contains the filename A_text_document_1234567890. I am using following for loop workaround to get the desired output, but I guess cut command can do a lot better than this. Here, I have chosen the number of characters to be exactly 4, but you could substitute any number(s) you like. if [ "${#line}" -lt "25" ] then First, it's usually better to be explicit about your intent. -name "FILE_NAME" | xargs -I name grep PATERN name Now I would like to only get the last line of the grep result for each single file. rtf}. Share. png bar I have following content in a file. ; It will output with CR line terminators for MAC line terminators. You should In this article, we explored different methods for extracting the last n characters of a string. One potentially-useful aspect of this approach is that if the string doesn't end in . ; s is the pattern replacement command. 123456 To: file. Often you may want to use Bash to get the last N characters from a string. sed -E 's/(. You can then grab the first (newest) with head -1. The awk command is a string processing tool that looks for a specific pattern inside a string and manipulates it. Improve this I have a text file which contains filenames and labels to this files Example String: 0-3081031014094495-0. Start Here; Guides Administration A collection of guides on Linux system administration Scripting Basic and advanced scripting on Linux. You can use the following basic syntax with the tail [[:digit:]] is a character class, i think it speaks for itself {5} means exactly five of the prior character, class (as in this example), or group must match; In english, you can think of it behaving like this: the FN string is iterated character by character until we see an _ at which point the capture group is opened and we attempt to match Here, the first $ points to the last line within the file, the “. ls -t b2* | head -1 But beware: Why you shouldn't parse the output of ls My personal opinion: parsing ls is dangerous when the filenames can contain funny characters like spaces or newlines. My file contains the following data : hello mark this is the head line this is the first line this is the second line this is the last line the command above prints the data as: mark. Using “awk” Command. *} then, you get the last char: char=${name_no_ext: -1} #note the space after colon If you want to learn more about string manipulation in bash, go to section Parameter Expansion of the bash manual. \1 is a backreference which refers to the first capture group. Getting the last n characters. )-E means extended regex-o means print each matching part on a separate line; Share. Modified 3 years, 9 months ago. To get last character in a string in Bash scripting, you can use parameter expansion and substring expansion as shown in the following expression. {0,5}). Read first line from latest file. lastln=$(tail -n1 file) Then it is simply a matter of indexing the last characters, e. ; It will just output text for Linux/Unix "LF" line terminators. head and pipe with tail will be slow for a huge file. Removing first 3 characters of file names in linux. sed 'NUMq;d' file Where NUM is the number of the line you want to print; so, for example, sed '10q;d' file to print the 10th line of file. * does. Can somebody help? Get last number from a string: grep -Eo '[0-9]+' | tail -1 (Expanding on George's answer a bit. Here is an example: It should be a comment to the basename answer but I haven't enough point. # This could be whatever test defines an irrelevant line. " | tr "\n" "," Basically, you reverse the lines of the file, then split them with cut using space as the delimiter, take the first field that cut produces and then you reverse the token again, use tr -d to delete unwanted chars and tr again to replace newline Learn two ways to get the last word from each line of a file. If the file is large, this will be much faster than the Perl solution that was chosen as the best answer. The issue that you're running into is that your loop variable, file, will take the values of your filenames after they have all been concatenated into a single long string and then split on whitespaces (and after any split-up word that happens to be a globbing pattern has been 4. Desired output: 1234567890. Viewed 359 times 1 . *} to get the filename without the extension and ${file##*. Print last occurence of x (regex): grep x file | tail -1 Alternatively (should be faster because it reads from the end): tac file | grep -m1 x Print file from first matching line to end: awk '/x/{flag = 1}; flag' file Print file from last matching line to end (prints all lines in case of no match): tac file | awk '!flag; /x/{flag = 1};' | tac tail -n "+$(($(grep -n 'TERMINATE' file | head -n 1 | cut -d ":" -f 1)+1))" file It takes two processes to do what sed can do in one process, and if the file changes between the execution of grep and tail, the result can be incoherent, so I recommend using sed. When processing mulitple lines in a file, sed and awk are usually better tools but bash will get the job done. 2. $ slashes the last character only. Reading everything but first and last line into a I am trying to write a script that checks whether the user accidentally added an extra "/" to the end of a filepath (eg. Bash: Find specific files and cut last 5 characters from name . Short version: file -k somefile. Negative indices means the moving from the end to the start of the string so that -1 is index of the last character: Use sed with a capture group that matches the first 5 characters and returns only that group:. substring(var1. As all answers here does access same file two time, instead of just split them Here is my two cents: I have a file name (including an extension, but not a full path name) in variable file, and I want to only get the last 10 characters of the base name from a parameter expansion. answered Sep 20, 2019 at 15:23. Skip to main content. Explanation:-o (--only-matching) only outputs the part of the input that matches the pattern (the default is to print the entire line if it contains a match). -n is the number of characters we need to extract from the end of a string. For example, if you want to get the Nth character from an input string, you can use -cN which will extract the specific character. 1,838 11 11 silver badges 23 23 bronze badges. Ask Question Asked 9 years, 7 months ago. rtf, it is not changed at all; var2 will contain an unmodified copy of var. Bash I am having issues with a problem accomplished very easily in most languages but I can't seem to figure it out in batch. I want to extract the last character of a string. }" Outputs: filename: thisfile extension: txt Share. while IFS= The ls command has a parameter -t to sort by time. \{5\}\). MY_PATH) and if they did, it removes the last character. sed -n -e 's/^. offset . Moreover, if the file doesn’t not contain TERMINATE, the first command fails. No need for quoting the command. About; Products OverflowAI; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about I am trying to get a string after the last "/" character. Use the -c option with following a number which indicates the position of the character you want to extract. But i am unable to understand this because, head -2 is used to print the first two lines and tail -1 prints the last line but how come 2nd line is printed!!??? Bash: Get the Last Part of a String. The $ s/. g. My file structure is 256. c. $/z/' Share. lrnd txct oavruj stt tmu wlq ekslx kcay oxshn yfry vaypxg xldcmv hhaj wihzf zyzjx