wolfe@neon.stanford.edu (Michael R. Wolfe) (08/19/89)
I know how to call Unix commands from C: system(string), but I'm having trouble coming up with the commands in string form from inside of a program. That is, I'm being forced to do multiple strcat's to form a string to send to system. Is there a way around this? In addition, is there any way to find the result of a unix command called from C without having to send it to a file and then open the file. For example, I'm trying to use grep from C, which forces me to make a string such as "grep file >> anotherfile" using strcat, use "system" to call it, and then go and open "anotherfile" afterwards to find the result. Has anyone come up with a better way? -Mike
gwyn@smoke.BRL.MIL (Doug Gwyn) (08/19/89)
In article <11072@neon.Stanford.EDU> wolfe@neon.stanford.edu (Michael R. Wolfe) writes:
-... That is, I'm being forced to do multiple strcat's to form a
-string to send to system. Is there a way around this?
Yes: Use a single sprintf() into a character array of sufficnet size,
then call system with that array name as its argument.
-In addition, is there any way to find the result of a unix command
-called from C without having to send it to a file and then open
-the file.
See popen(3S) in your UNIX Programmer's Reference Manual.bzs@bu-cs.BU.EDU (Barry Shein) (08/21/89)
From: wolfe@neon.stanford.edu (Michael R. Wolfe) >I know how to call Unix commands from C: system(string), but >I'm having trouble coming up with the commands in string form >from inside of a program. That is, I'm being forced to do >multiple strcat's to form a string to send to system. Is there a >way around this? sprintf() should help a lot with this. >In addition, is there any way to find the result of a unix command >called from C without having to send it to a file and then open >the file. For example, I'm trying to use grep from C, which forces >me to make a string such as "grep file >> anotherfile" using strcat, >use "system" to call it, and then go and open "anotherfile" afterwards >to find the result. Has anyone come up with a better way? See popen(3) which returns a pipe to/from the command. -- -Barry Shein Software Tool & Die, Purveyors to the Trade 1330 Beacon Street, Brookline, MA 02146, (617) 739-0202 Internet: bzs@skuld.std.com UUCP: encore!xylogics!skuld!bzs or uunet!skuld!bzs