Shell Script String Manipulation

I'm trying to replace an epoch timestamp within a string, with a human readable timestamp. I know how to convert the epoch to the time format I need (and have been doing so manually), though I'm having trouble figuring out how to replace it within the string (via script).

The string is a file name, such 开发者_运维知识库as XXXX-XXX-2011-01-25-3.6.2-record.pb.1296066338.gz (epoch is bolded).

I've been converting the timestamp with the following gawk code:

gawk 'BEGIN{print strftime("%Y%m%d.%k%M",1296243507)}'

I'm generally unfamiliar with bash scripting. Can anyone give me a nudge in the right direction?

thanks.

You can use this

date -d '@1296066338' +'%Y%m%d.%k%M'

in case you don't want to invoke awk.

Are all filenames the same format? Specifically, "." + epoch + ".gz"?

If so, you can use a number of different routes. Here's one with sed:

$ echo "XXXX-XXX-2011-01-25-3.6.2-record.pb.1296066338.gz" | sed 's/.*\.\([0-9]\+\)\.gz/\1/'
1296066338

So that extracts the epoch, then send it to your gawk command. Something like:

#!/bin/bash

...
epoch=$( echo "XXXX-XXX-2011-01-25-3.6.2-record.pb.1296066338.gz" | sed 's/.*\.\([0-9]\+\)\.gz/\1/' )
readable_timestamp=$( gawk "BEGIN{print strftime(\"%Y%m%d.%k%M\",${epoch})}" )

Then use whatever method you want to replace the number in the filename. You can send it through sed again, but instead of saving the epoch, you would want to save the other parts of the filename.

EDIT: For good measure, a working sample on my machine:

#!/bin/bash

filename="XXXX-XXX-2011-01-25-3.6.2-record.pb.1296066338.gz"

epoch=$( echo ${filename} | sed 's/.*\.\([0-9]\+\)\.gz/\1/' )
readable_timestamp=$( gawk "BEGIN{print strftime(\"%Y%m%d.%k%M\",${epoch})}" )

new_filename=$( echo ${filename} | sed "s/\(.*\.\)[0-9]\+\(\.gz\)/\1${readable_timestamp}\2/" )

echo ${new_filename}

You can use Bash's string manipulation and AWK's variable passing to avoid having to make any calls to sed or do any quote escaping.

#!/bin/bash
file='XXXX-XXX-2011-01-25-3.6.2-record.pb.1296066338.gz'
base=${file%.*.*}     #    XXXX-XXX-2011-01-25-3.6.2-record.pb
epoch=${file#$base}   #    1296066338.gz
epoch=${epoch%.*}     #    1296066338
# we can extract the extension similarly, unless it's safe to assume it's ".gz"
humantime=$(gawk -v "epoch=$epoch" 'BEGIN{print strftime("%Y%m%d.%k%M",epoch)}')
newname=$base.$humantime.gz
echo "$newname"

Result:

XXXX-XXX-2011-01-25-3.6.2-record.pb.20110126.1225.gz