How to apply shell command to each line of a command output

Question

Suppose I have some output from a command  such as ls -1    a b c d e       I want to apply a command  say echo  to each one  in turn  E g   echo a echo b echo c echo d echo e       What s the easiest way to do that in bash

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i like to use gawk for running multiple commands on a list  for instance  ls -l   gawk   system   path to cmd sh   1      however the escaping of the escapable characters can get a little hairy

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You actually can use sed to do it  provided it is GNU sed         sed  s match command  0 e    How it works    Substitute match with command match On substitution execute command Replace substituted line with command output

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for s in  cmd   do echo  s  done   If cmd has a large output   cmd   xargs -L1 echo

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You can use a for loop    for file in     do    echo   file  done   Note that if the command in question accepts multiple arguments  then using xargs is almost always more efficient as it only has to spawn the utility in question once instead of multiple times

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Better result for me   ls -1   xargs -L1 -d   n  CMD

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xargs fails with with backslashes  quotes  It needs to be something like  ls -1  tr   n   0  xargs -0 -iTHIS echo  THIS is a file     xargs -0 option    -0  --null           Input  items are terminated by a null character instead of by whitespace  and the quotes and backslash are           not special  every character is taken literally    Disables the end of file string  which is treated  like           any  other argument   Useful when input items might contain white space  quote marks  or backslashes   The           GNU find -print0 option produces input suitable for this mode     ls -1 terminates the items with newline characters  so tr translates them into null characters   This approach is about 50 times slower than iterating manually with for      see Michael Aaron Safyans answer   3 55s vs  0 066s   But for other input commands like locate  find  reading from a file  tr   n   0  lt file  or similar  you have to work with xargs like this

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It s probably easiest to use xargs  In your case   ls -1   xargs -L1 echo   The -L flag ensures the input is read properly  From the man page of xargs   -L number     Call utility for every number non-empty lines read       A line ending with a space continues to the next non-empty line

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You can use a basic prepend operation on each line   ls -1   while read line   do echo  line   done   Or you can pipe the output to sed for more complex operations   ls -1   sed  s          echo  1

[bash] How to apply shell command to each line of a command output?

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