Recent questions tagged Unix

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unix - Concatenate multiple files but include filename as section headers

I would like to concatenate a number of text files into one large file in terminal. I know ... file2 awesomepossum file3 hownowbrowncow See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - Parent CMakeLists.txt overwriting child CMakeLists.txt output directory options

I am trying to place a library from a project into a certain directory in my build output, but the parent ... SUFFIX ".pyd") endif(WIN32) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - Find files containing multiple strings

I use a command to recursively find files containing a certain string1: find . -type f -exec grep -H string1 ... only two strings would be nice. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - Extract columns from a file based on header selected from another file

I have the following problem that I want to solve in awk. I have one large text table, comma separated, ... Thanks in advance for any help! See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - is there a way to use the equivalent of touch in powershell to update time stamps of a file?

I use the unix command 'touch' a lot to update time-stamps of any new acquired/downloaded file in my system. ... 5 as well as powershell 6. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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585 views

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unix - How to combine AND and OR condition in bash script for if condition?

I was trying to combine logical AND & OR in a bash script within if condition. Somehow I am not getting the ... out what is going wrong here? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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487 views

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unix - How do I delete a matching line and the previous one?

I need delete a matching line and one previous to it. e.g In file below I need to remove lines 1 & 2. I tried " ... document 1** **page 2 of 2** See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - deploying a website/webapp via git/gitolite permissions error

I've setup a development/testing server where developers can push repositories to a remote repo/webserver via ... would be really appreciated. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - binary operator expected error when checking if a file with full pathname exists

pathname=$(cat $HOME/.rm.cfg) if [ ! -z $pathname/$1 ] .rm.cfg is a file that contains the following ... give a binary operator expected error. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - How to tell if a Linux machine supports AVX/AVX2 instructions?

I'm on SUSE Linux Enterprise 10/11 machines. I launch my regressions to a farm of machines running Intel ... and Haswell family, respectively. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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524 views

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unix - Maximum buffer length for sendto?

How do you get the maximum number of bytes that can be passed to a sendto(..) call for a socket opened as a UDP port? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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635 views

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unix - Difference between write() and printf()

Recently I am studying operating system..I just wanna know: What's the difference between a system call (like ... function (like printf())? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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716 views

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unix - OpenSSL create SHA hash from shell stdin

How to generate the SHA-512 hash with OpenSSL from command line without using a file? I've tried this ... online-convert.com/sha512-generator). See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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635 views

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unix - Interpret as fixed string/literal and not regex using sed

For grep there's a fixed string option, -F (fgrep) to turn off regex interpretation of the search string. Is there a ... sed -i "s/abc/def/g" See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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563 views

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unix - How can I read from a specific raw file descriptor in Rust?

Editor's note: This question is for a version of Rust prior to 1.0. Some answers have been updated to cover ... Rust nightly before Rust 1.0. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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602 views

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unix - Purpose of square brackets in shell scripts

I came across this line in one of the shell scripts: [-f $host_something ] && .$host_something What are ... with the same environment variable? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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494 views

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unix - How can I determine if a python script is executed from crontab?

I would like to know how can I determine if a python script is executed from crontab? I don't want a solution ... module (not the main script). See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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555 views

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unix - C - Proper way to close files when using both open() and fdopen()

So I'm building a Unix minishell in C, and am implementing input, output, and err redirection, and have come ... to post anymore code just ask. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - how to delete all files except the latest three in a folder

I have a folder which contains some subversion revision checkouts (these are checked out when running a capistrano ... using one unix command? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unix - Explain this duplicate line removing, order retaining, one-line AWK command

I learned a really handy way to remove duplicate lines retaining the order from Remove duplicates without sorting ... precedence of operations? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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645 views

1 answer

unix - How to print ASCII value of a character using basic awk only

I need to print the ASCII value of the given character in awk only. Below code gives 0 as output: echo a | awk '{ printf("%d ",$1); }' See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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635 views

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unix - How do I turn off echo in a terminal?

I'm writing a Bourne shell script and have a password input like this: echo -n 'Password: ' read password Obviously ... go read the manpage. ;) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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776 views

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unix - Find out if a command exists on POSIX system

I want to be able to tell if a command exists on any POSIX system from a shell script. On Linux, I ... 9699919799/idx/utilities.html) Any ideas? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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699 views

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unix - How to use pipe within -exec in find

Is there any way to use pipe within an -exec in find? I don't want grep to go through whole file, but only ... , but couldn' t find any answers. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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704 views

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unix - Display exact matches only with grep

How can I display all jobs that ended OK only? When I try the command below, it shows both OK and ... ctmpsm -listall application | grep OK See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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673 views

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unix - Bash - How to call a function declared in a parent shell?

I am writing a bash script that calls functions declared in the parent shell, but it doesn't work. For ... function visible to the script? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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575 views

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unix - Python piping output between two subprocesses

I'm working on some code that will DD a block device over SSH, and I'm wanting to do this with subprocess ... is the correct way to do things. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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640 views

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unix - Cannot get cron to work on Amazon EC2?

I've spent two days trying to understand why I can not get cron to work on my Ubuntu EC2 instance. I' ... solutions? Thanks for your time. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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