RE: Cool shell tricks (was: Re: file system questions)
Hi, try this site for lots of tips an tricks http://www.linux.com/tuneup [Avishay Aton] -Original Message- From: Shaul Karl [SMTP:[EMAIL PROTECTED]] Sent: Sunday, October 22, 2000 1:36 AM To: [EMAIL PROTECTED] Subject: Re: Cool shell tricks (was: Re: file system questions) On Sat, Oct 21, 2000 at 08:23:44AM +0200, Shaul Karl wrote: Also, seems that not many people are aware of "process substitution" in bash: you do something like "diff (ls dir1) (ls dir2)", and bash runs two ls's, each writing to a FIFO, and diff gets the names of these two FIFOs as parameters. Output redirection also works. I'm not sure how portable it is, though. 1. [08:05:37 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) bash: syntax error near unexpected token `(l' [08:06:04 /tmp]$ Ache, the space there is significant: [08:17:12 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) Yeah... Otherwise it's redirection. I am confused. Without the space it is not a redirection? Is there a difference between a FIFO and a redirection? 2. This will only work if the "main" process (diff in this example) does not need to seek the input since it can not do it with a FIFO. Or am I missing something? True... You can't. It would've been nice if Bash had the option to use temporary files rather than FIFOs... But I don't know if it's needed that often. Just tried: both nvi and vim cope fine, Emacs refuses to read it (at least with default setup and switches). Less requires you to use -f. - Adi Stav = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] -- Shaul Karl [EMAIL PROTECTED] = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: Cool shell tricks (was: Re: file system questions)
On Tue, Oct 17, 2000 at 04:59:48PM +0200, guy keren wrote: there is a dirty method you could use. every once in a while (perhaps even via a cron job), execute the command: :/path/to/.xsession-error Cool. I love these little shell tricks... I'm personally particularly fond of the old "(cd dir1; tar c) | (cd dir2; tar xv)" thing, but it's been discussed here extensively before. Also, seems that not many people are aware of "process substitution" in bash: you do something like "diff (ls dir1) (ls dir2)", and bash runs two ls's, each writing to a FIFO, and diff gets the names of these two FIFOs as parameters. Output redirection also works. I'm not sure how portable it is, though. 1. [08:05:37 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) bash: syntax error near unexpected token `(l' [08:06:04 /tmp]$ Ache, the space there is significant: [08:17:12 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) 1,4c1 NOTE README README.xsetiathome amos --- Release_Notes.txt 8a6 result.sah 11c9 setiathome-3.0.i386-pc-linux-gnu-gnulibc2.1.tar --- setiathome_win_3_0.exe 14a13 windows_help.txt 16c15 xsetiathome --- wtemp.sah [08:18:20 /tmp]$ 2. This will only work if the "main" process (diff in this example) does not need to seek the input since it can not do it with a FIFO. Or am I missing something? Does anyone else like these tricks? I'd love to hear about other people's. - Adi Stav = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] -- Shaul Karl [EMAIL PROTECTED] = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: Cool shell tricks (was: Re: file system questions)
On Fri, Oct 20, 2000, Adi Stav wrote about "Cool shell tricks (was: Re: file system questions)": On Tue, Oct 17, 2000 at 04:59:48PM +0200, guy keren wrote: there is a dirty method you could use. every once in a while (perhaps even via a cron job), execute the command: :/path/to/.xsession-error Cool. I love these little shell tricks... I'm personally particularly fond .. Does anyone else like these tricks? I'd love to hear about other people's. When you know all the features of your shell (e.g., bash or zsh), it gives you incredible power - both for interactive use and for programming (zsh is a very capable programming language!). To wield this power wisely, you'll need to know what exactly is available to you, i.e., you should read the manual and/or texinfo documentation, and see what cool features your shell has :) 6 years ago I switched from using ATT's (David Korn's) ksh to using zsh because of a few features I was missing (such as smart completion). The Zsh executable was then much bigger than ksh (now on Solaris it is about 2.5 bigger) and at first I thought that it was bloatware, adding, besides the 2-3 features I wanted, 20-30 extra useless features. Since then I changed my mind - I've probably used each and every feature in zsh for something, and I can't believe I once settled for ksh :) -- Nadav Har'El|Saturday, Oct 21 2000, 22 Tishri 5761 [EMAIL PROTECTED] |- Phone: +972-53-245868, ICQ 13349191 |How much wood would a woodchuck chuck if http://nadav.harel.org.il |a woodchuck would chuck wood? = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: Cool shell tricks (was: Re: file system questions)
On Sat, Oct 21, 2000 at 08:23:44AM +0200, Shaul Karl wrote: Also, seems that not many people are aware of "process substitution" in bash: you do something like "diff (ls dir1) (ls dir2)", and bash runs two ls's, each writing to a FIFO, and diff gets the names of these two FIFOs as parameters. Output redirection also works. I'm not sure how portable it is, though. 1. [08:05:37 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) bash: syntax error near unexpected token `(l' [08:06:04 /tmp]$ Ache, the space there is significant: [08:17:12 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) Yeah... Otherwise it's redirection. 2. This will only work if the "main" process (diff in this example) does not need to seek the input since it can not do it with a FIFO. Or am I missing something? True... You can't. It would've been nice if Bash had the option to use temporary files rather than FIFOs... But I don't know if it's needed that often. Just tried: both nvi and vim cope fine, Emacs refuses to read it (at least with default setup and switches). Less requires you to use -f. - Adi Stav = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: Cool shell tricks (was: Re: file system questions)
On Sat, Oct 21, 2000, Adi Stav wrote about "Re: Cool shell tricks (was: Re: file system questions)": True... You can't. It would've been nice if Bash had the option to use temporary files rather than FIFOs... But I don't know if it's needed that often. Zsh has an additional process substition that looks like =(...), for example xdvi =(zcat file.dvi.gz) That creates a temporary file (a regular file, not a pipe) with the output of the command, and passes that name to another command. I use it very often - usually in the form of the example above. I almost never use the (...) form: while it can be more efficiant, the difference is barely noticable (on a modern computer) and many programs (including xdvi) can't handle pipes as input files because they want to be able to seek (rewind) into the file - so using temporary files instead of a the pipe is like a "better safe than sorry". I don't know if bash also has this form - check out its manual. -- Nadav Har'El|Saturday, Oct 21 2000, 22 Tishri 5761 [EMAIL PROTECTED] |- Phone: +972-53-245868, ICQ 13349191 |If God is watching us, the least we can http://nadav.harel.org.il |do is be entertaining. = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: Cool shell tricks (was: Re: file system questions)
On Sat, Oct 21, 2000 at 08:23:44AM +0200, Shaul Karl wrote: Also, seems that not many people are aware of "process substitution" in bash: you do something like "diff (ls dir1) (ls dir2)", and bash runs two ls's, each writing to a FIFO, and diff gets the names of these two FIFOs as parameters. Output redirection also works. I'm not sure how portable it is, though. 1. [08:05:37 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) bash: syntax error near unexpected token `(l' [08:06:04 /tmp]$ Ache, the space there is significant: [08:17:12 /tmp]$ diff (ls ~/setiathome/) (ls ~/setiathome/amos/) Yeah... Otherwise it's redirection. I am confused. Without the space it is not a redirection? Is there a difference between a FIFO and a redirection? 2. This will only work if the "main" process (diff in this example) does not need to seek the input since it can not do it with a FIFO. Or am I missing something? True... You can't. It would've been nice if Bash had the option to use temporary files rather than FIFOs... But I don't know if it's needed that often. Just tried: both nvi and vim cope fine, Emacs refuses to read it (at least with default setup and switches). Less requires you to use -f. - Adi Stav = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] -- Shaul Karl [EMAIL PROTECTED] = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Cool shell tricks (was: Re: file system questions)
On Tue, Oct 17, 2000 at 04:59:48PM +0200, guy keren wrote: there is a dirty method you could use. every once in a while (perhaps even via a cron job), execute the command: :/path/to/.xsession-error Cool. I love these little shell tricks... I'm personally particularly fond of the old "(cd dir1; tar c) | (cd dir2; tar xv)" thing, but it's been discussed here extensively before. Also, seems that not many people are aware of "process substitution" in bash: you do something like "diff (ls dir1) (ls dir2)", and bash runs two ls's, each writing to a FIFO, and diff gets the names of these two FIFOs as parameters. Output redirection also works. I'm not sure how portable it is, though. Does anyone else like these tricks? I'd love to hear about other people's. - Adi Stav = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
