Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
bash$ cat /proc/interrupts
CPU0
0: 84505 XT−PIC timer
1: 3375 XT−PIC keyboard
2: 0 XT−PIC cascade
5: 1 XT−PIC soundblaster
8: 1 XT−PIC rtc
12: 4231 XT−PIC PS/2 Mouse
14: 109373 XT−PIC ide0
NMI: 0
ERR: 0
bash$ cat /proc/partitions
major minor #blocks name
rio rmerge rsect ruse wio wmerge wsect wuse running use aveq
3 0 3007872 hda 4472 22260 114520 94240 3551 18703 50384 549710 0 111550 644030
3 1 52416 hda1 27 395 844 960 4 2 14 180 0 800 1140
3 2 1 hda2 0 0 0 0 0 0 0 0 0 0 0
3 4 165280 hda4 10 0 20 210 0 0 0 0 0 210 210
...
bash$ cat /proc/loadavg
0.13 0.42 0.27 2/44 1119
Shell scripts may extract data from certain of the files in /proc. [59]
bash$ cat /proc/filesystems | grep iso9660
iso9660
kernel_version=$( awk '{ print $3 }' /proc/version )
CPU=$( awk '/model name/ {print $4}' < /proc/cpuinfo )
if [ $CPU = Pentium ]
then
run_some_commands
...
else
run_different_commands
...
fi
The /proc directory contains subdirectories with unusual numerical names. Every one of these names maps
to the process ID of a currently running process. Within each of these subdirectories, there are a number of
files that hold useful information about the corresponding process. The stat and status files keep running
statistics on the process, the cmdline file holds the command−line arguments the process was invoked with,
and the exe file is a symbolic link to the complete path name of the invoking process. There are a few more
such files, but these seem to be the most interesting from a scripting standpoint.
Chapter 28. /dev and /proc 312