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Full Discussion: To reverse a string
Top Forums Shell Programming and Scripting To reverse a string Post 302715607 by pamu on Monday 15th of October 2012 06:46:58 AM
Old 10-15-2012
Quote:
Originally Posted by santhoshks
Thank you , it s working..
awk '{ for (i=NF;i>=1;i--) { if(s!= ""){s=s" "$i}else{ s=$i }} {print s;s=""}}' file

but i dint understand this part
if(s!= ""){s=s" "$i}else{ s=$i }} {print s;s=""}}... can you pls explain ?
awk perform operations line by line.
At first line we have no defined s yet. so just we check is s present or not.
Code:
if(s!= "")   # Check here s present or not if s presents the append next character to it. here you also can use if(s)
{s=s" "$i} # Here we do append part. All the words are appended in reverse manner.
else{ s=$i  }} # here we initialize s. s=$NF
{print s;s=""}} # and at the lat after end of for loop we print final s(which is reversed output of the input line) and make s="" ready to to next line

Hope this helps youSmilie
 

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SHTOOL-PATH.TMP(1)					      GNU Portable Shell Tool						SHTOOL-PATH.TMP(1)

NAME
shtool-path - GNU shtool command dealing with shell path variables SYNOPSIS
shtool path [-s|--suppress] [-r|--reverse] [-d|--dirname] [-b|--basename] [-m|--magic] [-p|--path path] str [str ...] DESCRIPTION
This command deals with shell $PATH variables. It can find a program through one or more filenames given by one or more str arguments. It prints the absolute filesystem path to the program displayed on "stdout" plus an exit code of 0 if it was really found. OPTIONS
The following command line options are available. -s, --suppress Supress output. Useful to only test whether a program exists with the help of the return code. -r, --reverse Transform a forward path to a subdirectory into a reverse path. -d, --dirname Output the directory name of str. -b, --basename Output the base name of str. -m, --magic Enable advanced magic search for ""perl"" and ""cpp"". -p, --path path Search in path. Default is to search in $PATH. EXAMPLE
# shell script awk=`shtool path -p "${PATH}:." gawk nawk awk` perl=`shtool path -m perl` cpp=`shtool path -m cpp` revpath=`shtool path -r path/to/subdir` HISTORY
The GNU shtool path command was originally written by Ralf S. Engelschall <rse@engelschall.com> in 1998 for Apache. It was later taken over into GNU shtool. SEE ALSO
shtool(1), which(1). 18-Jul-2008 shtool 2.0.8 SHTOOL-PATH.TMP(1)
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