Easy steps for optimizing shell scripts
Speedier Scripts

Shell scripts are often written for simplicity rather than efficiency. A closer look at the processes can lead to easy optimization.
A shell script is essentially a sequence of commands and branches. Listing 1 shows a typical example. query.sh
has all the basic components of a shell script. It contains keywords such as if
, then
, else
, and fi
; shell built-in commands such as echo
and read
; the square bracket; and last but not least, an external command (/bin/echo
).
The calls to echo
and /bin/echo
behave differently, although they give you the same results. To see the difference, call the script twice while monitoring the shell with the command strace
.
Listing 2 shows the first pass; Listing 3 uses Strace to display the corresponding output. At the start, the system creates a new shell process with a process identifier (PID) of 2489, which is responsible for processing the script. If you say y
at the prompt, the output appears and the script is terminated (Listing 3, last line).
[...]
Buy this article as PDF
(incl. VAT)