csh

The Perl manual describes a totally devious construct that will work under any of csh, sh, or Perl, such as the following : eval '(exit $?0)' && eval 'exec perl -wS $0 ${1+"$@"}' & eval 'exec /usr/bin/perl -wS $0 $argv:q' if $running_under_some_shell; Devious indeed... can someone please explain in detail how this works? The idea is that those three lines do 3 different things if they're evaluated in a standard Bourne shell (sh), a C shell (csh), or Perl. This hack is only needed on systems that don't support specifying an interpreter name using a #! line at the start of a script. If you

I have a csh script (although I can change languages if it has any relevance) where I have to: sed s/AAA/BBB/ file The problem is that AAA and BBB are paths, and so contain '/'. AAA is fixed, so I can say: sed s/\\\/A\\\/A\\\A/BBB/ file However, BBB is based on variables, including $PWD. How do I escape the '/' in $PWD? OR is there some other way I should be doing this entirely? Lev Levitsky sed can use any separator instead of / in the s command. Just use something that is not encountered in your paths: s+AAA+BBB+ and so on. Alternatively (and if you don't want to guess), you can pre-process

When I run the following command in csh , I got nothing, but it works in bash , is there any equivalent in csh which can redirect the standard error to standard out? somecommand 2>&1 The csh shell has never been known for its extensive ability to manipulate file handles in the redirection process. You can redirect both standard output and error to a file with: xxx >& filename but that's not quite what you were after, redirecting standard error to the current standard output. However, if your underlying operating system exposes the standard output of a process in the file system (as Linux does

How can I extract a word that comes after a specific word in Linux (csh)? More precisely, I have a file which has a single line which looks like this: [some useless data] --pe_cnt 100 --rd_cnt 1000 [some more data] I want to extract the number 100 which is after the --pe_cnt word. I cannot use sed as that works only if you want to extract an entire line. Maybe I can use awk? Also, I have multiple files that have different values instead of 100 so I need something that extracts the value but doesn't depend on the value. With awk : awk '{for(i=1;i<=NF;i++) if ($i=="--pe_cnt") print $(i+1)}'

I am converting a csh script to a python script. The script calls a memory-intensive executable which requires a very large stack, so the csh script sets the stacksize to unlimited: limit stacksize unlimited When I try to reproduce this script in python, I execute them in a very naive manner, using os.system , e.g.: os.system('some_executable') But I do not know how to tell the OS to run these executables with unlimited stacksize. Is there a way to specify stacksize for calls within a python script? Is there some low-level system call that I should be using? And is there a module (similar to

I am calling SQL*Plus from Linux C Shell: sqlplus username/password @file.sql var1 var2 var3 If I pass a string as var1 , how long can this string be? Is it governed by the OS? In this case: Linux version 2.6.9-100.ELsmp (mockbuild@x86-010.build.bos.redhat.com) (gcc version 3.4.6 20060404 (Red Hat 3.4.6-11)) #1 SMP Tue Feb 1 12:17:32 EST 2011 Update: Empirical testing yielded the following results: A command line argument of 5200 characters gave the error, "Word too long." 1300 characters then produced the SQL*Plus error, "string beginning "(000796384..." is too long. maximum size is 239