what's the meaning of clang -idirafter? - clang

execute calng --help | grep 'idirafter' will print:
-idirafter Add directory to AFTER include search path.
I can't totally understand this expression. What's the different between include and idirafter?

Related

grep: Find all files containing the word `star`, but not the word `start`

I have a bunch of files: some contain the word star, some contain the word start, some contain both.
I'd like to grep for files that contain the word star, but not the word start.
How can this be accomplished using only grep?
grep has some options for inverting the matches at the line or file level. You want the latter option, with the -L switch. The following will print the names of all the files in a folder that don't contain the text start:
grep -LF start *
-F tells grep that start is a literal string and not a regex. It's optional here, but might speed things up a tiny bit.
You can use the resulting list to search for files that contain star:
grep -lF star $(grep -LF start *)
-l prints only the names of files containing a match, not any line-by-line or match-by-match details. If this is not exactly what you want, man grep is your friend.
This uses an additional shell construct to run the inverted match, but it technically doesn't call any additional programs that aren't grep.
Update
Since you mention wanting to look through all the files starting with a given root folder, change -LF to -LFr. Replace * with your root folder if you don't want to change working directories.
-r tells grep to recurse into directories, and search every file it finds along the way.
With GNU grep for -w:
$ cat file
foo star bar
oof start rab
$ grep -w star *
foo star bar
or if you just want the names of the files containing star:
$ grep -lw star *
file
and to just find files to look in:
$ find . -maxdepth 1 -type f -exec grep -w 'star' {} \;
foo star bar

(bash) grep -i not making search case insensitive for input files

I am trying to search inside a folder containing several files. The name of the files is written in upper case with a .sub extension in lower case:
AAA.sub
BBB.sub
CCC.sub
DDD.sub
I am searching a pattern trough those file using grep, however i would like to only use lower case letter for the input files.
In the man page for grep it is written:
-i, --ignore-case
Ignore case distinctions in both the PATTERN and the input files. (-i is specified by POSIX.)
So, if i understood properly:
grep -i subckt /schematics/aaa
and
grep -i subckt /schematics/AAA
Are supposed to both be able to search a pattern "subckt" in the file "aaa" regardless of its case (AAA or aaa) and if two files named aaa and AAA are present at the same time in the foler, i expect grep to search trough both of them.
However when i try my search with the 1st instruction (lower case) it does not work, giving me "no such file or directory" message.
When i try to search with the 2nd instruction (upper case) it works properly.
I obviously understood something wrong about how the -i option with grep, can anyone give me an answer regarding this matter?
Is it possible to be case insensitive with the input files when using grep?
EDIT:
My question was lacking details, even tough i have found the answer to my problem i will add the details in case someone else stumbles upon this:
I have one file that contains a list of each file name i want to grep. My list looks like this:
aaa capacitor C_0
bbb capacitor C_0
ccc resistor R_in
...
The grep is done inside a perl script, the perl script parses the list file and gets the name of each individual file name (aaa bbb ccc) inside a while loop.
However the name inside the list file is written in lower case whereas the name of the files i want to grep is written in upper case.
This is why i wanted to have the input file search to be case insensitive so that i could directly do a grep -i subck aaa and it would search inside the file 'AAA'
However, since the grep is launched from a perl script, and since it is apparently not possible to have grep behave like that, i used the uc() function of perl to convert aaa to AAA and do my grep with it. (see my answer below)
-i affects how the contents are searched, not the name of the files.
When the man page says "Ignore case distinctions in both the PATTERN and the input files." that really means that case is ignored in the pattern ( searching for AAA and aaa are equivalent) and the contents of the input files (a line would match if it includes "AAA" or "aaa" or even "AaA")
I think you want to either list all the filenames on the command line, or find a glob (i.e. wildcard) that matches all the filenames:
grep -i subckt *.sub
In Unix/Linux shells (bash, zsh, and so on) "*" is processed by the shell (bash) not the command (grep). The command receives the list of files and actually can't tell the difference between whether a user typed "grep foo *" and "grep foo file1 file2 file3" (if the directory includes those 3 files)
Please try the following command
find . -iname aaa.sub | grep -rn subckt
find with -iname option will list out files ignoring their case. In the above case find . -iname will list out both aaa.sub & AAA.sub. The output is piped to the grep command.
I have found a way to circumvent my problem by using the uc (upper case) function of perl to convert the input files for the grep function into upper case.
The grep command was launched from a perl script in the first place:
grep -i subckt /schematics/aaa
So, i just did that in my perl script:
$tmp=aaa
$tmp=uc($tmp)
grep -i subckt /schematics/$tmp
Now, the "aaa" name is just an example. In the perl script it is recovered from another parsed file that is written in lower case.
Thanks for the answers tough.
grep uses the filenames as they are listed on the command line. The -i option affects the contents of the files, not the names of the files.
You can use find to select filenames to be searched. The -iname option lets you match files ignoring case.
grep subckt $(find /schematics -iname aaa.sub -print)
If you have many filenames, or those filenames include spaces or other characters that would confuse the shell, the safe and secure way to do this is using the -print0 and -0 options:
find /schematics -iname aaa.sub -print0 | xargs -r -0 grep -i subckt

Search dot files in current directory

What's a simple way to grep just the dot files (.*) in the current directory ($HOME)? Using
grep target .*
returns a lot of nonsense:
grep: foo is a directory.
I don't want to see the nonsense.
grep has an option -s :
-s, --no-messages
Suppress error messages about nonexistent or unreadable files.
so you can just do grep -s 'target' .*

grep with --include and --exclude

I want to search for a string foo within the app directory, but excluding any file which contains migrations in the file name. I expected this grep command to work
grep -Ir --include "*.py" --exclude "*migrations*" foo app/
The above command seems to ignore the --exclude filter. As an alternative, I can do
grep -Ir --include "*.py" foo app/ | grep -v migrations
This works, but this loses highlighting of foo in the results. I can also bring find into the mix and keep my highlighting.
find app/ -name "*.py" -print0 | xargs -0 grep --exclude "*migrations*" foo
I'm just wondering if I'm missing something about the combination of command line parameters to grep or if they simply don't work together.
I was looking for a term on a .py file, but didn't want migration files to be scanned, so what I found (for grep 2.10) was the following (I hope this helps):
grep -nR --include="*.py" --exclude-dir=migrations whatever_you_are_looking_for .
man grep says:
--include=GLOB
Search only files whose base name matches GLOB (using wildcard matching as described under
--exclude).
because it says "only" there, i'm guessing that your --include statment is overriding your --exclude statement.

grep in all directories

I have a directory named XYZ which has directories ABC, DEF, GHI inside it. I want to search for a pattern 'writeText' in all *.c in all directories (i.e XYZ, XYZ/ABC, XYZ/DEF and XYZ/GHI)
What grep command can I use?
Also if I want to search only in XYZ, XYZ/ABC, XYZ/GHI and not XYZ/DEF, what grep command can I use?
Thank you!
grep -R --include="*.c" --exclude-dir={DEF} writeFile /path/to/XYZ
-R means recursive, so it will go into subdirectories of the directory you're grepping through
--include="*.c" means "look for files ending in .c"
--exclude-dir={DEF} means "exclude directories named DEF. If you want to exclude multiple directories, do this: --exclude-dir={DEF,GBA,XYZ}
writeFile is the pattern you're grepping for
/path/to/XYZ is the path to the directory you want to grep through.
Note that these flags apply to GNU grep, might be different if you're using BSD/SysV/AIX grep. If you're using Linux/GNU grep utils you should be fine.
You can use the following command to answer at least the first part of your question.
find . -name *.c | xargs grep "writeText"

Resources