Sponsored Content
Top Forums Shell Programming and Scripting really basic for loop question Post 302326488 by Rhije on Thursday 18th of June 2009 04:56:20 AM
Old 06-18-2009
The IFS (input field separator) is set to whitespace characters by default (space, tab, newline). If you use the 'while read' combination, you can assign each line to a variable (basically just like pludi has shown), except you do not need to specify the IFS.

Code:
-bash-3.2$ cat test.txt | while read i; do echo $i; done;
serial: 23124
hostname: server1

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

A basic question of FOR loop

Hi, have a basic query. Please see the below code: list="one two three" for var in $list ; do echo $var list="nolist" Done Wht if I want to print only first/ last line in the list Eg one & three Regards er_ashu (3 Replies)
Discussion started by: er_ashu
3 Replies

2. Shell Programming and Scripting

Basic bash 'for loop' usage

Hi! I have a simple question about using a for loop. I'm trying to open up all the zip files in the currect directory with ark, but I am getting the error "bash: syntax error near unexpected token `for $i ; do ark $i ; done ; I looked in the info pages for bash, but I can't seem to figure... (2 Replies)
Discussion started by: Orange Stripes
2 Replies

3. Shell Programming and Scripting

Basic While loop won't exit...

Hi everyone - just like to say great forum...I've learned a lot off here but I just can't figure this one out...(first post) I'm writing a script to monitor a directory and email the latest modified file....(I realize there are better ways than I'm trying here...I don't like copying and pasting... (5 Replies)
Discussion started by: trevthefatty
5 Replies

4. Shell Programming and Scripting

Very Basic Question regarding "while" loop

Hi, I have a loop like this - while read item do // fire insert query done < itemList.txt The itemList.txt has say, 1000 records. Now what I do is that rhough another program, I make the itemList.txt EMPTY, but still the INSERT query keeps firing the sequence of records. ... (18 Replies)
Discussion started by: angshuman_ag
18 Replies

5. Shell Programming and Scripting

Unix Shell basic loop massive n00b

hey guys I would really appreciate some help, i need to do a project for a job that requires minimal UNIX scripting and im REALLY stuck basically Im stuck at what i believe is something really simple but i just dont have a clue how to do it efficiently and properly and i REALLY appreciate some... (16 Replies)
Discussion started by: thurft
16 Replies

6. Shell Programming and Scripting

Basic bash, echo in loop for

Hi, I am trying to make a script to manage log. I want to write the name of the .gz I moved and the date : for i in `ls $replog/*.gz` do echo " $i " `echo $i date +%d:%m:%Y` `echo $datee `>> $replog/mrnet.log mv $i /var/log/vieux-logs done I need to echo... (10 Replies)
Discussion started by: Dabless
10 Replies

7. Shell Programming and Scripting

Trying to run a basic for loop

OS : RHEL 6.1 Shell : Bash I had a similair post on this a few weeks back. But I didn't explain my requirements clearly then. Hence starting a new thread now. I have lots of files in /tmp/stage directory as show below. I want to loop through each files to run a command on each file. I... (8 Replies)
Discussion started by: kraljic
8 Replies

8. UNIX for Dummies Questions & Answers

Basic loop awk/shell script question..

Hi, Sorry if this is a newbie question. I guess you can use either awk or shell script for this sequence of operations, but knowing very little about either of them I'm not sure how I should try to write this. The basic objective is to copy certain files that are scattered all over my... (10 Replies)
Discussion started by: pc2001
10 Replies

9. Shell Programming and Scripting

Basic help improving for in loop

I'm obviously very new to this. I'm trying to write a simple for loop that will read the directory names in /Users and then copy a file into the same subdir in each user directory. I have this, and it works but it isn't great. #!/bin/bash HOMEDIRS=/Users/* for dirs in $HOMEDIRS; do if ];... (5 Replies)
Discussion started by: Heath_T
5 Replies

10. Shell Programming and Scripting

Basic FOR loop with break

Oracle Linux : 6.4/bash shell In the below I want to break out of the loop when it enters the 5th iteration. #!/bin/bash for i in 1 2 3 4 5 6 do echo "$i" if echo "Oh Nooo... i = $i. I need to stop the iteration and jump out of the loop" then break fi done But, it only... (3 Replies)
Discussion started by: John K
3 Replies
read(1)                                                            User Commands                                                           read(1)

NAME
read - read a line from standard input SYNOPSIS
/usr/bin/read [-r] var... sh read name... csh set variable = $< ksh read [ -prsu [n]] [ name ? prompt] [name...] DESCRIPTION
/usr/bin/read The read utility will read a single line from standard input. By default, unless the -r option is specified, backslash () acts as an escape character. If standard input is a terminal device and the invoking shell is interactive, read will prompt for a continuation line when: o The shell reads an input line ending with a backslash, unless the -r option is specified. o A here-document is not terminated after a NEWLINE character is entered. The line will be split into fields as in the shell. The first field will be assigned to the first variable var, the second field to the second variable var, and so forth. If there are fewer var operands specified than there are fields, the leftover fields and their interven- ing separators will be assigned to the last var. If there are fewer fields than vars, the remaining vars will be set to empty strings. The setting of variables specified by the var operands will affect the current shell execution environment. If it is called in a subshell or separate utility execution environment, such as one of the following: (read foo) nohup read ... find . -exec read ... ; it will not affect the shell variables in the caller's environment. The standard input must be a text file. sh One line is read from the standard input and, using the internal field separator, IFS (normally space or tab), to delimit word boundaries, the first word is assigned to the first name, the second word to the second name, and so on, with leftover words assigned to the last name. Lines can be continued using ewline. Characters other than NEWLINE can be quoted by preceding them with a backslash. These backslashes are removed before words are assigned to names, and no interpretation is done on the character that follows the backslash. The return code is 0, unless an end-of-file is encountered. csh The notation: set variable = $< loads one line of standard input as the value for variable. (See csh(1)). ksh The shell input mechanism. One line is read and is broken up into fields using the characters in IFS as separators. The escape character, (), is used to remove any special meaning for the next character and for line continuation. In raw mode, -r, the character is not treated specially. The first field is assigned to the first name, the second field to the second name, and so on, with leftover fields assigned to the last name. The -p option causes the input line to be taken from the input pipe of a process spawned by the shell using |&. If the -s flag is present, the input will be saved as a command in the history file. The flag -u can be used to specify a one digit file descriptor unit n to read from. The file descriptor can be opened with the exec special command. The default value of n is 0. If name is omitted, REPLY is used as the default name. The exit status is 0 unless the input file is not open for reading or an end-of-file is encoun- tered. An end-of-file with the -p option causes cleanup for this process so that another can be spawned. If the first argument contains a ?, the remainder of this word is used as a prompt on standard error when the shell is interactive. The exit status is 0 unless an end-of- file is encountered. OPTIONS
The following option is supported: -r Does not treat a backslash character in any special way. Considers each backslash to be part of the input line. OPERANDS
The following operand is supported: var The name of an existing or non-existing shell variable. EXAMPLES
Example 1: An example of the read command The following example for /usr/bin/read prints a file with the first field of each line moved to the end of the line: example% while read -r xx yy do printf "%s %s " "$yy" "$xx" done < input_file ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of read: LANG, LC_ALL, LC_CTYPE, LC_MES- SAGES, and NLSPATH. IFS Determines the internal field separators used to delimit fields. PS2 Provides the prompt string that an interactive shell will write to standard error when a line ending with a backslash is read and the -r option was not specified, or if a here-document is not terminated after a newline character is entered. EXIT STATUS
The following exit values are returned: 0 Successful completion. >0 End-of-file was detected or an error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), ksh(1), line(1), set(1), sh(1), attributes(5), environ(5), standards(5) SunOS 5.10 28 Mar 1995 read(1)
All times are GMT -4. The time now is 09:00 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy