Shell script to read a file line by line in unix. But its taking a long time to read the file line by line.

Let’s see how to read a file using a while and a for loop. (In my case, I have to make a script that changes all the passwords into hash value) Here is a sample input Aug 10, 2015 · Use an extra read inside a compound command. There might be instances where you want to read the contents of a file line by line using a BASH script. read LINE does the following: read Aug 6, 2013 · I would like to store each record in the array word by word. " You find line 1, and move it to the top. txt ----- 112040108174516. txt $ time awk NR==334227 myfile. the reason for this is that the file is an exported database from excel to csv so the first line would contain titles like first name dob enrolled etc etc and is not needed Consider a file. My closest attempt so far: Dec 27, 2016 · If you need to read a file line by line and perform some action with each line – then you should use a while read line construction in Bash, as this is the most proper way to do the necessary. Jul 4, 2015 · How do I read line by line from standard input in Bash? Until now I used "read string" but I do not think that it reads a line at a time. arr[0]=abc, arr[1]=2, arr[2]=1 and so on and after reading first line it will read line 2 and store its value like: arr[0]=cba, arr[1]=1, arr[2]=2 and so on I have tried below code Mar 31, 2024 · Now, you can see that the file is read including backslashes by the read command in a while loop. Can you hel | The UNIX and Linux Forums If your script is reading content from files, the above listed will not work. Inlining on the loop works too. I tried #!/bin/sh # My first Script echo "Hello World!" Dec 25, 2013 · Hi, I need to read a text file from shell script line by line and copy the feilds of each line. To use the character = as the field delimiter, set the variable IFS for the read command. shell scripts. I've tried this: declare -a array=(`cat "file name"`) but it didn't work, it extracts the whole lines Jul 15, 2017 · I have a problem with reading a file line by line with bash script. How to Create Your First Bash Script Jun 9, 2012 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. Issues with Reading Line by line from a file. The prototype for read is: read [options] name[s ] read will read a line of input into name name1 name2 splitting the line based on the contents of the Internal Field Separator (IFS). Suppose i have a file test. Nov 26, 2008 · Hello there, I have a script that I would like to read a file line by line and launch a function with the entire line as a parameter. Like for line 1 . /programname file. e, one line from file1 and one line from file2, next line from file 1, next line from file2, and so on. But it is reading the values by spaces. The file sid_home. Script I wrote is Jun 9, 2014 · I want to make the script to start reading from the second line only, i cant get it working. The following shell doesn't works. That code will effectively empty out the line separator for your read command and set it to its default. txt contains any IFS characters (by default, including <space> and <tab>). txt` if ;then exit 1 fi Now I have to start checking file names, i. If you have a CSV file with single or even multiple columns, you can do these line by line "diff" operations using the sqlite3 embedded db. Something like: variable1=test1 variable2=test2 . when the input is pgm2 then the shell script should have statements for copying file21, file22 etc and so on. How to do it in perl. Nov 17, 2008 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. Just use that. Using “cat” Command. txt gets generated as expected, but the script (6 Replies) Hi, I want to read a live log file line by line and considering those line which start from time stamp[2013-04-21 21:55:16,435]; Below code I am using, which read line but throws an exception when com | The UNIX and Linux Forums Jul 3, 2012 · I am a newbie in Unix I have a file which contains a list of file names. 235s sys 0m0. Please help pre { overflow:scroll; margin:2px; | The UNIX and Linux Forums Jun 23, 2018 · And, it is much more efficient and more likely to work than the loop you suggested above. However, by definition you'll have to iterate through all the records since the operating system has no way to parse line-oriented files since files are byte-oriented. Tags. File colour. It comes with python, so should be available on most linux/macs. sh. Oct 27, 2010 · I try to make a small script, using c shell, that will take a file made of several lines, each containing a name and a number and sum all numbers that a have certain name. After I read it line by line there are some commands in which I have to change a specific string. If all you want to do is echo the input back to output, cat does that already. Though, be careful! If the process/script is trapped and read was cancelled while reading input (e. Here is the script: shell script to read file line by line does not work Read content of May 25, 2014 · IFS is a variable for the line separator (or actually "Internal Field Separator"). With script bash, read file line per line starting at the end. Page 1 of 2 using the awk command $1 refers to the first column and $2 to the second column. file directory is common for all the files. txt Jan 23, 2012 · Hi, I am a beginner in shell scripting. For reading a large file, using a loop is efficient because it is very effective for reading each line of a large file. . So far, online I have only seen stuff like sed, (I can only use the sh -not bash or sed or anything like that). Whenever it comes across those words it would record the line number so I can later shoot the text file off in an email with the problem lines. Sep 2, 2020 · Using awk to extract fields from the line works (apart from the mangling from echo), but it's overly complicated and slow. Use the following script to read line by line content of a file using the while loop: Aug 18, 2016 · I want to read a file line by line in Unix shell scripting. But I'm getting the 'end of file' unexpected for the last line. mp3" then the way you're reading it doesn't work. Edit: It seems all the solutions here are pretty slow. txt |tail -1 my_searched_line real 0m5. While reading I must find the line references from the another file. Now find line 3 and move it to the top. awk #!/bin/awk -f function test(var){ some code} { } END { print"test code" } (5 Replies) Feb 11, 2024 · Method 3: Read File Line by Line Using Loop. Jan 3, 2021 · To read the file line by line, you would run the following code in your terminal: while IFS= read -r line; do printf '%s\n' "$line" done < distros. i have a text file as belows, it includes 2 columns, 1st is the column name, 2nd is the file_name data_file. 1. Both of these files are in the same directory. Shell script to read a text file line by line & process it Mar 31, 2022 · In the example below, my user has the rwx (read, write, execute) rights for the file test_script. The code reads the file by line, assigns each line to a variable, and prints it. Create your a. But its taking a long time to read the file line by line. Jun 8, 2009 · Hi All, i want to write a shell script read below file line by line and want to exclude the lines which contains empty value for MOUNTPOINT field. Jul 20, 2010 · That would give you the <lineno> lines, then only give the last line of output (your line). In this section, we will look at different ways to do just that. How can i pass that value from my shell script ?? I know I can change perl script to default the answer but i dont have access to do that so only option i (5 Replies) Can those questions maybe be merged somehow? Both have some really good answers that highlight different aspects of the problem, the bad answers have in-depth explanations in the comments what's bad about them, and as of now you cannot really get a whole overview on what to consider, from the answers of one single question from the pair. txt file and store it in a array @test. The name of newly generated file should come from the line content. txt 920391 myfile. txt file with below values one,two three,four five,six six,seven red,tree Need a shell script command to perform below activity For loop in which the loop should be continuously Oct 6, 2009 · The most robust and simplest way to read a file line-by-line and preserve all spacing is: $ while IFS= read -r line || [[ -n $line ]]; do printf "'%s'\n" "$line"; done </tmp/test. Wraper script am trying is to do with above metion 2 files. The idea of the file is that each will contain server information, such as IP address and various port numbers. I thought a "while read file; do" was my answer but the only way I know how to script with that loop is reading FILE BY FILE, not LINE Aug 8, 2011 · In a vast majority of cases, you should avoid this. This is more efficient than using a separate process to skip the first line, and prevents the while loop from running in a subshell (which might be important if you try to set any variables in the body of the loop). . 3. txt The file can have different number of other files names or nothing I will check cnt=`wc -l file_name_0. csv files Nov 1, 2011 · awk will process line by line by default. 963s user 0m1. So: "Find every line that has a beginning, and move it to line number 0. | The UNIX and Linux Forums Jul 11, 2009 · the shell script has to read the text file and if the input given is pgm1 then the shell script shoud copy the file to some directory. In my input file I have 5 spaces appended at the end of each line. This way of reading produces a combined file output in which lines are alternated between the files. read txt file line by line. Executable scripts appear in a different colour from rest of the files and folders. How can I put into a vari Aug 29, 2008 · Hi, In ksh we use ‘while read line’ statement to read a file line by line. txt), which reads the file's Dec 10, 2015 · So I need to read line by line and store each line value seprated by delimeter in different variable. Method 1 – Using simple loop. Shell Script to Read File. How to do this in a bash shell script? Sample line in my comma separated file 123,2014-07-21 10: Oct 20, 2005 · Hi All, i want to write a shell script read below file line by line and want to exclude the lines which contains empty value for MOUNTPOINT field. I am trying to copy every file in the same directory but with a different extension. In this case, the text of the line is added to a set a, and execution skips to the next line of input. thanks Venu (3 Replies) Jun 24, 2016 · I have a file called "test_file1". Sep 21, 2009 · #!/bin/sh ## This will read a file line by line x=`wc -l $1 |awk '{print $1}'` echo "No of lines are: $x \n" i=1 while [ $i -le $x ] do echo "Line Number: $i -->\n" echo "`head -$i $1 | tail -1` \n" i=`expr $i + 1` done Jun 29, 2009 · The UNIX and Linux Forums. 126s $ time head -334227 myfile. Can you all share some thoughts on this one. inp2. 725s $ time sed '334227!d' myfile my_searched_line Nov 8, 2013 · Using ksh on AIX what I am trying to do is to read the ls -l output from a file in a do while loop line by line. something like while ifs=, read (from second line) var 1 var 2 var3 etc. I am also writing the each file name to t | The UNIX and Linux Forums Dec 19, 2013 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. 2. Feb 6, 2017 · How to extract a file content into array in Bash line by line. csv and b. thanks Venu (3 Replies) I am new to shell scripting. I wrote something that reads the file word after word. A workaround could look like the following example. Cat my. Line can contain leading and trailing spaces and i want to read those spaces also in the line. txt. 0 means "top of the file, before the current line 1". Dec 15, 2017 · Read content of file line by line in unix using 'line' Ask Question Asked 6 years, 6 months ago. Forum Home. I have developed a script which reads a record and checks the below scenario. txt) and store it in a array (@test) How to do it in perl. In my case, the scripts with execution rights appear as green. In addition, some might want -r read option to not process backslashes (escapes). I have a file and my task is to read the file and generate a new file for each line. You can script the sqlite3 commands on the bash shell without needing to write python. Jun 8, 2012 · Basically I want to have a shell script that just goes through a text file, line by line, and searches for the words "Error" or "Exception". The idea of the file is that each will contain server information, such as IP a | The UNIX and Linux Forums POSIXly, you can use IFS= read -r line to read one line off some input, but beware that if you redirect the whole while read loop with the input file on stdin, then commands inside the loop will also have their stdin redirected to the file, so best is to use a different fd which you close inside the loop: Apr 18, 2015 · Read a file line by line in a shell script. Does nothing. This is an example o May 9, 2011 · Folks , i want to read a csv file line by line till the end of file and filter the text in the line and append everything into a variable. The script does not read the last line in the text file 2. The combined size of all the | The UNIX and Linux Forums Sep 22, 2010 · I've tried it couple of times to avoid the file cache and found the head + tail was quick but the ruby was the fastest: $ wc -l myfile. Jun 3, 2016 · this is suppose to be the users input file when calling the program from the terminal. txt 'Line 1' ' Line 2 has leading space' 'Line 3 followed by blank line' '' 'Line 5 (follows a blank line) and has trailing space ' 'Line 6 has no ending CR' Sep 26, 2017 · Hi, I am calling a Perl script in my shell script. Feb 23, 2010 · I have a file file_name_O. Aug 30, 2012 · FOLKS , i have a text file that is generated automatically of an another korn shell script, i want to bring in the fifth line of the text file in to my korn shell script and look for a particular word in the line . There's a shell builtin that reads a line and splits it into fields: read. g. Here is a technique that works without requiring nested loops: Apr 16, 2012 · Hi , I have a number of files having an average line count of 10,000 lines. I have written the following script, which is supposed to process the while loop for each line in the sid_home. When Perl script is executed it asks for a answer to be entered by user from terminal. Modified 6 years, Shell script read a file line by line. txt 112040108174516 | The UNIX and Linux Forums Jul 5, 2012 · In this article, we will see different ways in which we can read 2 files in parallel line by line, i. Feb 7, 2008 · Dear all, I am reading a file that has 1 column. i am using centos 7 Operating system. I have to read each line of the test. txt gets generated as expected, but the script (6 Replies) Feb 24, 2009 · Hi All, i want to write a shell script read below file line by line and want to exclude the lines which contains empty value for MOUNTPOINT field. – Apr 14, 2008 · Hi, I am a beginner in shell scripting. In this example, the cat command is piped with the while read -r line to read line from the file. Nov 27, 2009 · If you simply want to echo each line out with its tabs and spaces on the end of each line then you can use nawk: - Jul 6, 2010 · Hi All, Do we know how to read input file within awk script and send output toanother log file. In this article i will show the general syntax of the while read line construction in Bash and an example of how to read a file line by line from the Oct 12, 2013 · I am trying to get a specific line from a text file. I need to do this only using a Instead of reading it line by line, execute it as a shell script. I've text file which contains Jul 20, 2024 · Explains how to read a file line by line under a UNIX/macOS/*BSD/Linux by giving the filename as an input to a bash/ksh while read loop. I have to read each file line by line and output the parsed lines into one single output file. I am running this awk through crontab. I need to read all the files in that direcory and search for certain criteria in each file and write into a outputfile. – Jun 15, 2015 · @1_CR Thanks. I had attempted to use cut, but cut does not accept \\n (newline) as a delimiter. txt file. May 12, 2010 · Hello ; i need a script which can read a file line by line. Apr 14, 2015 · And inside my shell script I need to read this input file line by line to get to a variable like this: things="House,Monkey,Car" I know this sounds easy, but I just couldnt find any simple solution for this. Thus when reading from file, only the (FNR in a) case applies, and prints the text of the relevant line if its number was put in a in parsing file_with_linenr. txt, and will not work correctly if any filename contained in file_name_0. I tried with "while read line" but read command is removing space characters from line :( Example if line in file are:-abcd efghijk abcdefg hijk Ordinarily, you should read from a file using a while read -r line loop. Aug 29, 2008 · In ksh we use 'while read line' statement to read a file line by line. want to read below file. Apr 4, 2010 · To explain: FNR==NR will occur only when reading file_with_linenr, not file. su -c to the user and change directory/file permisions to 777. Brief: This example will help you to read a file in a bash script. Then find line 2 and move it above line 1, to the top of the file. Aug 30, 2011 · FOLKS , i have a text file that is generated automatically of an another korn shell script, i want to bring in the fifth line of the text file in to my korn shell script and look for a particular word in the line . Make sure that you can trust this file, since you'll be executing whatever is in there, including rm -rf ~ or some such. Very often the processing could take place in an Awk script and the shell while read loop just complicates matters. e. Your has to start up another shell for the command substitution, run the cat utility to get the contents of file_name_0. Regards Harikrishna (3 Replies) Jan 19, 2016 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. We will use BASH commands and tools to achieve that result. Using While Loop to Read file. Sep 1, 2018 · and because it's running glob expansion, it doesn't emit exactly what's in the file. Each line is set to an element. awk '{print}' <file name> will process line by line giving you the option to add whatever process you need to execute on the all the lines. The file has these two lines: My name is hello world My Name is not hello world What I want is the following: File 1 should have 1 record and name of this file is fourth field of row which Jun 3, 2014 · How can I read this line by line? Esentially I want to read filepath1 and run a command based on it's correlation with the country on the same line, then move onto the next line (filepath2 then filepath3 etc. Leading and trailing whitespaces will be kept intact and backslash will not be intepreted as an escape character Oct 18, 2012 · I need to execute the file with 69lakh records and load it to a table. within the second 'elif' within the script I included a 'break' - the script runs successfully (except for the first (2 Replies) Apr 13, 2009 · 0 is which line to move to. Below is the complete requirement. csv file format is :- pre { overflow:scroll; margin:2px; padd | The UNIX and Linux Forums Nov 8, 2010 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. Mar 1, 2020 · Hi all I have spent half a day trying to create a shell script which reads a configuration file on a line by line basis. I thought this added flexibility (such as one loop could process the first N lines of the files and a second loop process the rest) and also the explicit open and close might look more familiar to the OP who appears to have a python background. txt gets generated as expected, but the script (6 Replies) Feb 19, 2011 · Hello, I have got a script that reads a text file, and have got three problems that I an struggling with. 569s sys 0m0. Ideally I want to loop through the file and store each word of the record in array and manipulate and print it again in record by record ((ie one array per record and as I am looping through I can do the manipulation ,print the new record and use the same array for next record) . Oct 2, 2014 · I currently have a problem that I need to read a file line by line. " trap "pkill -f 'sleep 1h'" INT trap "set +x ; sleep 1h ; set -x" DEBUG < YOUR CODE HERE > To stop the script you would have to kill it from another shell in this case. sh If the input file contains lines like "02 - Beautiful Emptiness. Apr 24, 2008 · Hi All Please help me , i have one big problem I need to read this files line bye line and print take it as arugument for another command fileslist. Ctrl+C), IFS may stay customized inside the trapped function/event. When I use while read line statement it chops off the spaces at the end of each line Given a text file with multiple lines, I would like to iterate over each line in a Bash script. Example. thanks Venu (3 Replies) Nov 22, 2021 · In this article, we are going to see how to read a file line by line in Bash scripting. This tutorial contains two methods to read a file line by line using a shell script. | The UNIX and Linux Forums Dec 3, 2012 · Shell script UNIX to read text file line by line. Jan 10, 2012 · HI I need to read each line (test. You can use while read loop to read a file content line by line and store into a variable. All this needs to be in awk script, not in command line. Jul 24, 2012 · FOLKS , i have a text file that is generated automatically of an another korn shell script, i want to bring in the fifth line of the text file in to my korn shell script and look for a particular word in the line . txt my_searched_line real 0m14. Aug 9, 2008 · Then go read the 2nd line and go on i t | The UNIX and Linux Forums i want to write a shell script read below file line by line and want to exclude the lines Nov 24, 2014 · Shell script UNIX to read text file line by line. I need to read a file that works in all shells that has variables defined in it. But once we write a shell script we can use the read line to read the whole line or we can use read number to read the first word,am I right?So my question is in the above if I wanted to read the second column how would I do that without using awk command from a Hi everybody, I have a config file what looks like this pre { overflow:scroll; margin:2px; padding:15px; border:3px inset; margin-right:10px; } Code: # name name #host TYPE-IFTYPE-user{ # hardware eth | The UNIX and Linux Forums Aug 12, 2011 · Hi , I have few files in a directory . I want to read each line of this file and write it to another file called "test_file2". In this case you should be doing Nov 3, 2014 · Hi All, Am trying to write wrapper shell/bash script on a utility tool for which i need to pass 2 files as arugment to execute utility tool. 524s user 0m0. #!/usr/bin/env bash echo "Press CTRL+C to proceed. And because it's performing a command substitution operation, it's extremely inefficient -- it's actually fork()ing off a subshell with a FIFO attached to its stdout, then invoking /bin/cat as a child of that subshell, then reading the output through the FIFO; compare to $(<file. To do this and parse the words on the lines requires nesting a for loop inside the while loop. Extract the user name(3rd field) and the directory/file name(9th field) using awk and save them into variables. Repeat this for every line. Like: . I want to read a file and save it in variable, but I need to keep the variable and not just print out the file. Feb 13, 2015 · I want to read a file in cshell line by line. When I use while read line statement it chops off the spaces at the end of ea Aug 31, 2012 · Hi, I am a beginner in shell scripting. For Ex, my file1 : Nov 11, 2010 · The UNIX and Linux Forums. shell; unix; sh; reading a line from file Jun 24, 2005 · Sorry for the short info : im using the ksh on a sun/solaris and the input data is as following: To describe the input data is quite complicated, but in a nutshell : I have a a flat-ascii file which contains directory-names. Hello, I'm works on Ubuntu server My goal : I Aug 12, 2014 · I want to read a file line by line, split each line by comma (,) and store the result in an array. zf gn cm tf nb zy xp lv wi zc