It’s join -t ‘|’ file1 file2 -a1 Options used: t: Delimiter. a: Decides the file number from which the unpaired lines have to be printed. join -t ‘|’ file1 file2 -a2 would do a right outer join. Sample Run [aman@aman test]$ cat f1 01|a|jack|d 02|b|ron|c 03|d|tom|e [aman@aman test]$ cat f2 01|a|nemesis|f 02|b|brave|d 04|d|gorr|h [aman@aman test]$ … Read more
You can use the shell variable $? Such as: $ true ; echo $? 0 $ false ; echo $? 1
scale = 20 It sets the number of decimal places. $ bc bc 1.06 Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty’. 355/113 3 scale=20 355/113 3.14159292035398230088 quit $
You need to use awk: awk ‘{print $1,$3}’ <namefile> This simple command allows printing the first ($1) and third ($3) column of the file. The software awk is actually much more powerful. I think you should have a look at the man page of awk. A nice combo is using grep and awk with a … Read more
find . -name \*.h -print -o -name \*.cpp -print or find . \( -name \*.h -o -name \*.cpp \) -print
use split: my_program | tee >(split -d -b 100000 -) Or if you don’t want to see the output, you can directly pipe to split: my_program | split -d -b 100000 – As for the log rotation, there’s no tool in coreutils that does it automatically. You could create a symlink and periodically update it … Read more
From O’Reilly: One marked difference between the System V and POSIX semaphore implementations is that in System V you can control how much the semaphore count can be increased or decreased; whereas in POSIX, the semaphore count is increased and decreased by 1. POSIX semaphores do not allow manipulation of semaphore permissions, whereas System V … Read more
Setting directories g+s makes all new files created in said directory have their group set to the directory’s group. This can actually be really handy for collaborative purposes if you have the umask set so that files have group write by default. Note: This is the way it works in Linux, it could work completely … Read more
awk -v x=2 ‘{print $x}’ or in a shell script: #!/bin/sh num=$1 awk < /tmp/in -v x=$num ‘{print $x}’ > /tmp/out
Excerpt from an interview with Ken Thompson (9-6-89): Every time we made a directory, by convention we put it in another directory called directory – directory, which was dd. Its name was dd and that all the users directories and in fact most other directories, users maintain their own directory systems, had pointers back to … Read more