There are many-many files in a directory that has e.x.: the following content:


root    1324711901
sshd    1272725792

And I'm searching for a solution how to convert the content of the files to this:


filenameXXX.txt root    1324711901
filenameXXX.txt sshd    1272725792


filenameXXX.txt root    Sat Dec 24 08:31:41 CET 2011
filenameXXX.txt sshd    Sat May  1 16:56:32 CEST 2010

So two things needed in two phases:

INPUT -> "filenameXXX.txt " before the first column -> OUTPUT1

OUTPUT1 -> convert unix times to normal times -> OUTPUT2

How to do this using bash OR sed OR perl? [don't need in all only 1 is enough :D]

ehh..and I need it in two part [so two one-liner]:

Field separators are "\t"-s [tabs]!

  • Is the first field (that looks like usernames) guaranteed to not contain spaces? Nov 4, 2011 at 6:34
  • no, it doesn't contain any spaces Nov 4, 2011 at 16:38

1 Answer 1


I prefer gawk for this:

awk -vOFS='\t' 'NF{$1=FILENAME OFS $1;$2=strftime("%c",$2)}1' filename.txt

Here is one perl alternative too:

perl -nae 'print$ARGV,"\t",$F[0],"\t".localtime($F[1]),"\n"' filename.txt

As you also asked about bash, here is what it could do:

while read -r who when; do
  readlink -n /proc/$$/fd/0
  echo -en "\t$who\t"
  date -d "@$when"
done < filename.txt

Regarding sed, its usage would be hard and the benefit would be insignificant as it is unable to tell the name of its input file and to convert date.

  • field separators are "tabs" Nov 4, 2011 at 16:39
  • your a living GOD :) [question updated! sry!] Nov 4, 2011 at 16:42
  • Answer updated too.
    – manatwork
    Nov 4, 2011 at 17:12
  • @manatwork: Thanks; a good answer!...I like that method of getting the filename from fd/0.. Will it always return the fully-qualified path?
    – Peter.O
    Nov 5, 2011 at 0:45
  • @fered, sadly man 5 proc not mentions that. Other symlinks like /dev/fd/0 and /dev/stdin usually point directly to /proc/$$/fd/0. Other symlinks like /proc/self/fd/0 indirectly points to the same file: actually /proc/self/ points to /proc/$$/. So many links in different places pointing to each other, would be hard to follow in case of relative links. So I would never expect to find relative links there. Of course, all these /proc/ and /dev/ related things are system specific in some aspects, may not apply exactly to Unix and BSD.
    – manatwork
    Nov 5, 2011 at 12:28

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