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Top Forums Shell Programming and Scripting Unable to print last line in Linux in while loop Post 303046032 by RudiC on Wednesday 22nd of April 2020 04:57:43 AM
Old 04-22-2020
The problem is not IFS's contents, which is used as a field separator between the individual fields. Your read is missing the line terminator, usually <LF> (= \n = 0x0A = ^J) which is not printfed. So read waits for it but runs into an EOF / EOT (as stdin terminates), discards the data read so far, and breaks out of the loop having unprocessed data in the variable(s) (Thanks to MadeInGermany's post#5 for mentioning that). You can
- add a linefeed <LF> to the printf command
- switch read to use a different line terminator (which still needs to be printfed). man bash:


Quote:
read
-d delim
The first character of delim is used to terminate the input line, rather than newline.
sea's proposal will set IFS to " ", "\", and "n", split input on any collection of those, and eliminate them from input. Set IFS like IFS=$' \n' to make it <space> and <line feed>.

Last edited by RudiC; 04-25-2020 at 02:59 PM..
 

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read(1) 						      General Commands Manual							   read(1)

NAME
read - read a line from standard input SYNOPSIS
var ... DESCRIPTION
reads a single line from standard input. The line is split into fields as when processed by the shell (refer to shells in the first field is assigned to the first variable var, the second field to the second variable var, and so forth. If there are more fields than there are specified var operands, the remaining fields and their intervening separators are assigned to the last var. If there are more vars than fields, the remaining vars are set to empty strings. The setting of variables specified by the var operands affect the current shell execution environment. Standard input to can be redirected from a text file. Since affects the current shell execution environment, it is usually provided as a normal shell special (built-in) command. Thus, if it is called in a subshell or separate utility execution environment similar to the following, it does not affect the shell variables in the caller's environment: Options recognizes the following options: Do not treat a backslash character in any special way. Consider each backslash to be part of the input line. Opperands recognizes the following operands: var The name of an existing or nonexisting shell variable. EXTERNAL INFLUENCES
Environment Variables determines the internal field separators used to delimit fields. RETURN VALUE
exits with one of the following values: 0 Successful completion. >0 End-of-file was detected or an error occurred. EXAMPLES
Print a file with the first field of each line moved to the end of the line. while read -r xx yy do printf "%s %s " "$yy" "$xx" done < input_file SEE ALSO
csh(1), ksh(1), sh(1), sh-posix(1). STANDARDS CONFORMANCE
read(1)
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