Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
DIRECTORY="/usr/X11R6/bin"
# Try also "/bin", "/usr/bin", "/usr/local/bin", etc.
for file in $DIRECTORY/*
do
whatis `basename $file`
done
# Echoes info about the binary.
exit 0
# You may wish to redirect output of this script, like so:
# ./what.sh >>whatis.db
# or view it a page at a time on stdout,
# ./what.sh | less
vdir
See also Example 10−3.
Show a detailed directory listing. The effect is similar to ls −l.
This is one of the GNU fileutils.
bash$ vdir
total 10
−rw−r−−r−− 1 bozo bozo 4034 Jul 18 22:04 data1.xrolo
−rw−r−−r−− 1 bozo bozo 4602 May 25 13:58 data1.xrolo.bak
−rw−r−−r−− 1 bozo bozo 877 Dec 17 2000 employment.xrolo
bash ls −l
total 10
−rw−r−−r−− 1 bozo bozo 4034 Jul 18 22:04 data1.xrolo
−rw−r−−r−− 1 bozo bozo 4602 May 25 13:58 data1.xrolo.bak
−rw−r−−r−− 1 bozo bozo 877 Dec 17 2000 employment.xrolo
locate, slocate
The locate command searches for files using a database stored for just that purpose. The slocate
command is the secure version of locate (which may be aliased to slocate).
$bash locate hickson
/usr/lib/xephem/catalogs/hickson.edb
readlink
Disclose the file that a symbolic link points to.
strings
bash$ readlink /usr/bin/awk
../../bin/gawk
Use the strings command to find printable strings in a binary or data file. It will list sequences of
printable characters found in the target file. This might be handy for a quick 'n dirty examination of a
core dump or for looking at an unknown graphic image file (strings image−file | more
might show something like JFIF, which would identify the file as a jpeg graphic). In a script, you
would probably parse the output of strings with grep or sed. See Example 10−7 and Example 10−9.
Example 12−26. An "improved" strings command
Chapter 12. External Filters, Programs and Commands 182