sh -c 'S=askapache R=htaccess; find . -mount -type f|xargs -P5 -iFF grep -l -m1 "$S" FF|xargs -P5 -iFF sed -i -e "s%${S}%${R}%g" FF'

FAST Search and Replace for Strings in all Files in Directory

I needed a way to search all files in a web directory that contained a certain string, and replace that string with another string. In the example, I am searching for "askapache" and replacing that string with "htaccess". I wanted this to happen as a cron job, and it was important that this happened as fast as possible while at the same time not hogging the CPU since the machine is a server. So this script uses the nice command to run the sh shell with the command, which makes the whole thing run with priority 19, meaning it won't hog CPU processing. And the -P5 option to the xargs command means it will run 5 separate grep and sed processes simultaneously, so this is much much faster than running a single grep or sed. You may want to do -P0 which is unlimited if you aren't worried about too many processes or if you don't have to deal with process killers in the bg. Also, the -m1 command to grep means stop grepping this file for matches after the first match, which also saves time.
Sample Output
Cpu(s): 28.1% us,  9.5% sy,  3.0% ni, 48.6% id,  9.9% wa,  0.2% hi,  0.7% si

  PID NI  %CPU %MEM  COMMAND
20707 19  0.0  0.1   sh -c S=askapache;R=htaccess;find . -type f|xargs -P5 -iFF grep -l -m1 "$S" FF|xargs -P5 -iFF sed -i -e s%${S}%${R}% FF
20708 19  2.0  0.0   find . -type f
20709 19  2.0  0.0   xargs -P5 -iFF grep -l -m1 askapache FF
20710 19  0.5  0.0   xargs -P5 -iFF sed -i -e s%askapache%htaccess% FF
23291 19  0.0  0.0   grep -l -m1 askapache ./servers/util_ldap_cache_mgr.c.html
23293 19  0.0  0.0   grep -l -m1 askapache ./servers/util_md5.c.html
23308 19  0.0  0.0   grep -l -m1 askapache ./servers/waitio.c.html
23310 19  0.0  0.0   grep -l -m1 askapache ./servers/winconfig.h.html
23311 19  0.0  0.0   grep -l -m1 askapache ./servers/wintty.c.html
23265 19  0.0  0.1   sed -i -e s%askapache%htaccess% ./servers/apr_uri.h.html
23266 19  0.0  0.0   sed -i -e s%askapache%htaccess% ./servers/apr_uri.c.html
23267 19  0.0  0.0   sed -i -e s%askapache%htaccess% ./servers/apr_time.h.html
23268 19  0.0  0.0   sed -i -e s%askapache%htaccess% ./servers/apr_user.h.html
23269 19  0.0  0.0   sed -i -e s%askapache%htaccess% ./servers/apr_strmatch.h.html

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